Misschien helpt dit: kijk of xfwm4 wordt gestart bij opstarten, en maak de cache eens leeg.
http://askubuntu.com/questions/47445/massive-xubuntu-desktop-malfunctionNo worries about the desktop settings, they were quickly restored. I'm granting you the answer because it points to the culprit -- xfwm4, the window manager. However, I managed to avoid starting it manually. Just started it once, then deleted the contents of ~/.cache/sessions/, and it now starts by itself. Hopefully this will be of help to other people
I have just upgraded to 3.2.0-32-generic #51-Ubuntu SMP Wed Sep 26 21:33:09 UTC 2012 x86_64 x86_64 x86_64 GNU/Linux
and had the same problem, the xfwm4 vanished from the startup applications and the mouse was incredibly slow.
After I add that in the startup apps, all works fine now.