Erratic mouse behavior in 12.04

[Marcelo Magno T. Sales]

Hello,

I'm running Kubuntu 12.04 64 bits fully updated and I'm experiencing some 
strange mouse behaviors, completely reproducible in this machine (Dell 
Inspiron One 2320). I have three others (vaio notebook and two Dell notebooks) 
where this problem does not happen. Some examples:
1. In libreoffice Calc, if I hover the mouse over the zoom control bar in the 
bottom right corner of Calc's window, the mouse grabs the zoom control by 
itself, without me clicking any button. If I move the mouse left and right, 
without ever touching its buttons, it drags the zoom control left and right.
2. In libreoffice Calc, if I left-click a tab other than the currently 
selected one, the new tab is selected as expected, but the mouse behaves as if 
the clicked button had stuck. When I move the mouse after selecting another 
tab, the mouse cursor changes to the arrow with the little rectangle, as if it 
was dragging a cell.
3. In Chromium, if I right-click a link and left-click "Open link in new tab", 
the mouse behaves as if the left-click stuck. When I move the mouse after 
opening the new tab, the mouse cursor changes to the little hand grabbing a 
sheet, as if I was moving the clicked link.
4. In Chromium, if I middle-click a link to open it in a new tab and then 
left-click the newly opened tab, the mouse cursor changes to the cross with 
arrowed points (the move window cursor) and the window is restored, as if I 
had started to drag it and let it go right after.

Until now, I haven't noticed such mouse problems when using native KDE 
applications, except that sometimes I'm under the impression that the mouse 
cursor image is not updating correctly according to context (arrow, text 
insertion cursor, etc.).
Any idea on what could be causing this?

Thanks,

Marcelo