"Error: Could not find or load main class My.class"
===

Im using Java SDK 1.7 on Windows 7 via cmd.exe . Up until a few hours ago everything was working correctly when suddenly I was unable to run my compiled class files, consistently presented with the error in the title.

I seem to be able to compile my My.java file however I am unable to run the resulting class file (My.class). I am constantly given the error "Error: Could not find or load main class My.class". I have tried this with multiple other class files all resulting in the same problem. 

My 'Path' environment variable is set to "C:\Program Files (x86)\Java\jdk1.7.0_05\bin" if you were wondering

I have tried reinstalling, creating and setting a classpath variable (no luck), and even directly using the "java -cp . My.class" command. 

I have tried these posts all to no avail, hence why I'm posting:

http://stackoverflow.com/questions/7485670/error-could-not-find-or-load-main-class

http://stackoverflow.com/questions/8966266/error-could-not-find-or-load-main-class-novice

http://stackoverflow.com/questions/7647448/could-not-find-or-load-main-class

http://stackoverflow.com/questions/9343977/java-1-7-0-03-error-could-not-find-or-load-main-class

If it makes any difference my code is :

    import javax.swing.JOptionPane;
    
    class My {
    	public static void main(String[] args) {
    	   final double x = 3.2;
    	   int i = (int)x;
    	   double m = 0;
    	   if (x < 4) {
    	      String saySomething = JOptionPane.showInputDialog(i);
    	      System.out.println(saySomething);
    	    }
    	   else {
              String saySomething = JOptionPane.showInputDialog(i);
    	      System.out.println("Hello World");
    	    }
    	   while (m < 10) {
    	        System.out.print(" While Loop ");
    			m++;
    		};
    	   for (i=1; i < 10; i++) {
    	       System.out.println("For Loop");
    	    };
    		
    	}
    }