I've been asked by my parent's to help them with their computer (windows 7) today, but I'm afraid I ran out of ideas. It could be a virus, but they had the latest Kaspersky AntyVirus installed on their computer, and I'm pretty sure they weren't browsing any suspicious russian webisites in their free time.  The PC boots without errors, but after that, basically everything stops working.   I cannot open any .exe file - not only Internet browser, AntiVirus and all the other "basic" programs, but also regedit or cmd, and even Task Manager.  Also, in the bottom right part of the screen when you can usually see most of the programs running in the background, like AntiVirus, wi-fi printer etc. there is only 1 icon, some weird blue logo with chinese signs as a description (according to google, it's the logo of Tencent).   All the other programs that should be opened after launching the pc aren't there, and what's more - the internet is also turned off, even though the router is right next to the desk.  I'm sure the system isn't completely frozen - I can see the mouse and browse through directories, but besides that, nothing works.   Is there anything I can do, besides reinstalling the entire OS?
What should I do if my Windows computer seems to be infected with a virus or malware?  What are the symptoms of an infection? What should I do after noticing an infection? What can I do to get rid of it? how to prevent from infection by malware?   This question comes up frequently, and the suggested solutions are usually the same. This community wiki is an attempt to serve as the definitive, most comprehensive answer possible. Feel free to add your contributions via edits.
Microsoft Edge missing in Start menu and pins Note: People have seem to have had issues doing this in Windows 10 pro, this could be because of Windows Updates. If the solution does not work, please use "Refresh your PC"  I have just upgraded to Windows 10 and had to switch to a Microsoft account while setting up Cortana.   Along the process, it asks me to sign out and sign back in, which I do. Then after signing back in, Microsoft Edge is missing. From the taskbar, and the "All Apps" section of the start menu.   This only occurs AFTER I have added my Microsoft account. And the only way is to open a .HTML file like this one:    (The name was from my Windows 7 Dualboot Install)  and please don't say "Just open the HTML file!" I need a proper solution to this. Suppose that, for a real application, I have ended up with a sorted list A = {$a_1, a_2, ..., a_{|A|}$} of elements of a certain kind (say, Type-A), and another sorted list B = {$b_1, b_2, ..., b_{|B|}$} of elements of a different kind (Type-B), such that Type-A elements are only comparable with Type-A elements, and likewise for Type-B.  At this point I seek to count the following: in how many ways can I merge both lists together, in such a way that the relative ordering of Type-A and Type-B elements, respectively, is preserved? (i.e. that if $P_M(x)$ represents the position of an element of A or B in the merged list, then $P_M(a_i)&lt;P_M(a_j)$ and $P_M(b_i)&lt;P_M(b_j)$ for all $i&lt;j$)  I've tried to figure this out constructively by starting with an empty merged list and inserting elements of A or B one at a time, counting in how many ways each insertion can be done, but since this depends on the placement of previous elements of the same type, I've had little luck so far. I also tried explicitly counting all possibilities for different (small) lengths of A and B, but I've been unable to extract any potential general principle in this way. Dual boot windows 8 and Ubuntu with Windows 8 Boot manager Show that $\frac{1}{x_1^2}+\frac{1}{4\cdot x_2^2}+\ldots+\frac{1}{n^2\cdot x_n^2}\leq\frac{3n-2}{2n-1}$. Let $$x_n=\frac{1}{1^2}+\frac{1}{2^2}+\ldots+\frac{1}{n^2},\;\forall n\geq 1.$$ Show that $$\frac{1}{x_1^2}+\frac{1}{4\cdot x_2^2}+\ldots+\frac{1}{n^2\cdot x_n^2}\leq \frac{3n-2}{2n-1}.$$   I tried to prove it by induction  but I got a contradiction. From Wikipedia: Fermi was known for his ability to make good approximate calculations with little or no actual data, hence the name. One example is his estimate of the strength of the atomic bomb detonated at the Trinity test, based on the distance travelled by pieces of paper dropped from his hand during the blast. Fermi's estimate of 10 kilotons of TNT was remarkably close to the now-accepted value of around 20 kilotons, a difference of less than one order of magnitude.  I have not been able to find any references explaining how he made this calculation. Please provide a reference or an example calculation.  See also: Why does Hermione say she hadn't used a memory charm before? After the wedding, Hermione has to use a memory charm on two Death Eaters, where she states that she has never done it before, but she knows the theory. However, she states that before she left on her adventure, she made her parents forget her, and move to Australia. Is this a contradiction, or is there an explanation? GCD in polynomial rings with coefficients in a field extension Modelling a spiral around a sphere I'm trying to figure out the best way to model the sphere-spiral here:    Is it possible to make this shape directly? Or do you have to make it as a cylinder and wrap it to a sphere? Why do we need both using namespace and include directives in C++ programs?  For example,   #include &lt;iostream&gt;  using namespace std;  int main() {  cout &lt;&lt; "Hello world"; }   Why is it not enough to just have #include &lt;iostream&gt; or just have using namespace std and get rid of the other?  (I am thinking of an analogy with Java, where import java.net.* will import everything from java.net, you don't need to do anything else.) Editing default custom object home screen I would like to add a custom button (URL to Flow) to my default home page for my custom object. Currently, I have a default "New" button to create a new record (see attached screen shot). I'm wanting to add my Flow custom button to this page. Is there a way to do this?  Cheers, Sean. Tuning PostGIS for production environments? What PostGIS documentation have you come across that has been helpful when tuning PostGIS for a production environment?  I would like to get together with my DBA to setup a Postgresql/PostGIS installation that is fit for production. I have read that there is some tweaking involved to achieve this, and I was hoping to find the answer on the .  So far I have found some documents on the OpenGeo site helpful, .  And this  is the kind of information I have found helpful, this is probably just basic DB stuff but to me its good stuff.  I would be interested to see what resources have helped others in achieving a stable production installation of PostGIS. How long does it take for reputation on Stack Overflow Careers to be updated? Just curious how this works:  My Stack Overflow reputation on my Stack Overflow CV shows an amount X, which is less than my actual Stack Overflow reputation Y. It's been this way for a few days. In addition, some of my 'favorite answers' on my CV have a lower # of votes than they do in reality.  How long does it take for this (I assume cached) value to be updated? Satisfying explanation of Aristotle's Wheel Paradox. The paradox:    We have a circle and there is another circle with smaller radius. They are co-centeric.  If circle make full turn without sliding, both smaller and bigger circle make full turn too. If we assume that the passed road is equal to the circumference of circles. We have got smaller circle's radius is equal to bigger one's.  Unsatisfying Solutions I found:    "Do not assume that smaller circle's circumference is equal to passed road since the surface that contacts to the ground is bigger one. " // Okey but it does not explain the paradox, it explains just what is the wrong assumption (even does not explain why it is a wrong assumption.) It is undeniable that every point on both smaller and bigger circle will contact exactly one and only one point on their path. Therefore we can think that this is a bijective maps and smaller circle is isomorphic to bigger one. (Okey but ....)   Question: What is the true answer? What is wrong with the definition of circumference of a circle and relationship with its taken path. How to automatically reinvest in non-dividend paying funds I've read Einsteins quote stating "The most powerful force in the universe is compound interest." However, everywhere I read this is basically only possible with dividend paying stocks and then applying a dividend reinvestment plan.  Is there a re-investing strategy like this for non-dividend paying mutual funds (or even non-dividend paying stock)? I figured that the only way would be to sell all your funds and then buy x+1 funds again, but this would cause a big loss because of transaction costs from the broker. Which browsers are officially supported, and what else do I need? Which browsers are officially supported by Stack Exchange?  Also, what else is needed in order to use every feature of the site? How does some of the black hole (BH) mass escape the event horizon (EH) of either BH, or the merged EH of two merged BHs? How to get coloured terminal over ssh? When I connect over ssh to remote hosts everything is just a single font/color. I would like to have colours like I do locally e.g. green for executable and blue for symlinks etc. And such that when I run $ git diff on the ssh host it shows me diff with colours =) What is the "Templates" folder in the home directory for? For as long as I can remember, every time I install Ubuntu there is a folder in the home directory called "Templates." I've always just deleted it, but I'm curious: what's it supposed to be used for, and why is it in the default install? Asymptotic expansion of $u_{n + 1} = \frac12 \arctan(u_n)$ Series where the planet’s air is really polluted and there is a portal to take you to a world where the air is clean The movie was released in the last 15 years, probably between 2008-2018. &quot;Pre-movie&quot; (like what happens before the main part of the movie begins):  The movie was in the future. The people have to wear gas masks to go outside because the air is so polluted. airpollution smog 2 child policy they had 3 kids the guy goes to prison There is some sort of transportation portal that brings some important people 85mio years in the past on another timeline The guy runs to the portal and gets there with his entire family  &quot;Main movie&quot; (most of the movie):  The guy is on this new planet and I think he gets imprisoned. The people built a camp with walls because there are dinosaurs that can easily kill people. Then a few other things happen I don't clearly remember. I think there is also some sort of love story. Then the dinosaurs attack the camp and they have to defend it.