Damn, I should have do that

Thanks for your reply.
I will try, when it happens again.
Before that - imagine Acrobat Reader, all seems OK, but there is no document inside visible. I can scroll or print, but nothing there on screen, like no document is loaded.
Second issue - imagine picture in browser, Firefox - picture is divided to several parts with blank spaces. If I switch the tab, picture completelly disappears.
Third - program dialog window is transparent and window behind it is visible - only dialog text is visible.
"Reload display driver" in RivaTuner helps.
(Excuse my "english" pls.)