Alt + tab working only randomly

[Naranek]

I recently upgraded to Kubuntu 11.04 and my alt+tab for desktop switching started to act up. It only works for about one out of three to six times. I tried setting the alt+tab shortcut to mute to see where the problem is, and it worked perfectly. So it seems that the keystroke is recorded, but cover switching isn't activated all the time. I tried disabling the effect (Effect for cover switching: None) but it doesn't help.

I've been able to troubleshoot my way out of pretty much everything so far, but now I'm out of ideas. What could cause this?

I'm have a Nvidia 9600GT card with a dual screen setup. I'm mentioning this just in case, because there's been some trouble with the driver before.

[Naranek]

OK, so it has something to do with the dual screen. I switched from Separate X screen to Twinview and now Alt+Tab works flawlessly. Any ideas what to do to get it working in Separate screen mode as well?

[Naranek]

OK so now I'm running 11.10 and the problem persists. If I'm in twinview clone mode everything's fine, but when I switch to separate screen dual head mode, the program switcher works only some of the time when pressing alt-tab. Any ideas?