When I open an excel spreadsheet that has multiple sheets it seems that on random sheets the screen doesn't refresh, What I mean by this is when I scroll through the sheet the information overlaps itself and doesn't refresh. I thought it was the video card at first but wouldn't it not refresh on all screens and in other programs not only in excel? I've tried repairing excel but the problem persists. If I minimize excel and re-maximize excel the screen is back to normal but as soon as I start to scroll it doesn't refresh and overlaps all of the information overtop itself, but not on every worksheet. I have transferred those same excel files to another computer with Excel 2010 and it works fine on those computers, so that tells me its not the spreadsheet. Also I have tested it with excel being the only program running.