Sometimes after computer wakes up after the hibernate mouse stops working: mouse pointer is visible and moves as it should, one of the konsole windows is getting the clicks regardless of whether is is focused and text can be selected there with a mouse but other than that there is no reaction to mouse events - windows cannot be lowered, raised or minimized etc, panel is not getting clicks, etc. Loks like KWin stops getting mouse events.

Problem started after the upgrade to 4.6.2 (ubuntu 10.10 to 11.04), MSI 890GXM-G65 motheboard (AMD 890GX/SB850), Logitech M705 wireless USB mouse.

If you run "kwin --replace" in Konsole when this happens, is it solved? Also, try looking in ~/.xsession-errors to see if there is anything mentioned, and check for "kscreenlocker" or similar processes - they may have failed to capture screen focus properly.