I have this problem since about 2 or 3 weeks, i was thinking it was related to the new driver for the graphicscard...
I have a dual monitor system and when i click from fullscreened Maniaplanet on the desktop on the second monitor, then i have to wait about 30 - 50 sec. until i'm able to use my mouse (the mouse cursor still has the style from Maniaplanet). If i use the ALT+Tab to switch to one of the programms on the main monitor, then i can e.g. reload a website by using the CTRL+R keys, but still not able to use the mouse.
After waiting 30 - 50 sec. i'm able to use the desktop as usual.
EDIT: Forgot to mention it: When i switch back from the desktop to Maniaplanet i have to wait again about 10 - 20 sec. until the screen from Maniaplanet is to see.
EDIT2: When the game is running in Windowed mode, then i can switch without any sleepings. It switch the same fast as any other programms.
EDIT3: Here my last log from 2013-02-05 with some fails at the end on closing Maniaplanet:
http://nopaste.info/bdfb5fae68.html