Well, try to right-click the folder that the MW2 Lib is in.
And change some settigs there.
I know that AVG used to put most of your folders ''blue''. I don't remember what that was again.
Try to google around for settings or so for AVG.
I think that is causing the problem.
Else, just move the MW2 Lib to another folder.
Make a new folder on your desktop and put MW2 Lib there.