X stops receiving mouse clicks

[Emanuele Tamponi]

Hello,
First of all, my configuration is: KUbuntu 9.04, Xorg 1.6 (KUbuntu default) 
with NVidia driver (KUbuntu default), configured with TwinView (Main: 1680x1050 
Secondary: 1280x800 (Laptop Display)). Xorg uses HAL to find input devices 
(AllowEmptyInput is set to true). I have a Wireless USB Keyboard+Mouse Set 
(and obviously the Trackpad in the laptop, and the laptop keyboard). I use KDE 
4.2.2 (KUbuntu default).

The problem: sometimes, and it happens most frequently when I leave the pc 
alone for some hours, *some* or *all* the parts of my desktop stop receiving 
mouse clicks. Most of the time, I can still click *only* on the Panel (but not 
always).
Replication is difficult: it appears to happen completely at random. The only 
solution currently is to restart X.
The keyboard keeps working flawlessy.
I tried to detach the wireless set, but this doesn't solve the problem.

Surfing the web, it looks like it may be related with Xinerama/TwinView. I 
tried to disable both, and the problem still occours.

Thanks in advance,
Emanuele