Comment 67 for bug 510004

Well that's unfortunate. It rejects our theory that X wasn't keeping the window data around and was leaving that up to the graphics card, which may have dropped the data during the resume.

So this is really getting close to the "we can't support nvidia closed source driver" issue, but perhaps Bryce Harrington has some more thoughts. This issue is pretty well outside of the kernel team's expertise at this point.