why is my website resizing browser windows
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I have had a report that my company's website is resizing at least one employee's browser windows. I experienced this behavior myself on the user's computer, and it was mystifying because the resizing only occurred on our site, not on any other site, and it occurred on both Firefox and Internet Explorer. The user has a Windows 7 machine running updated software. She has no add-ons, themes, or plugins besides the usual (Flash etc.) and her settings are the factory defaults. I cleared the browser cache on both browsers and restarted the computer and it still occurred.  The only thing left is the css, but none of it seems suspicious to me.

What is happening is, when she clicks a button or internal link on the site, then when the new page finishes loading, the browser window resizes to approximately 80% of the width of the content.  That is, the very last thing the page does as it loads is to resize itself. If she zooms in or out, then on the next load, it again resizes to 80% or so of the smaller or larger size of the content.  If she maximizes and then loads a page, then the window resizes to 80% but somehow maintains the "maximized" icon.  (You then have to click twice on the "maximized" icon to maximize.)

The reason I am flummoxed is that I thought this kind of behavior was something you could only do with JavaScript, but I deliberately tested this with pages that had no JavaScript at all and it still occurred.  There is exactly one page on the website that has browser-resizing JavaScript on it, but it resizes to a pixel size, not a percentage, and it's part of a web service that wasn't in use while I was testing.

What kinds of things should I investigate to solve this issue?  Because this is an employee, I have to either fix the website or fix her computer, so ideas for investigating both would be great. 