Ubuntu 12.04 with Cinnamon DE screen freezes

[SuperFreak]

I am getting frequent freezing of my computer screen while in Cinnamon DE. Mouse moves but I can't click on anything and CTL ALT DEL does not get me out. I can use CTL ALT F2 I think to get to a black screen with a command interface. If I restart manually and login to another interface I don't get freezing.

Recently in Cinnamon DE the panels disappeared and Firefox had a barely usable screen (no max min close buttons). So I removed Cinnamon and reinstalled from the stable PPA(http://ppa.launchpad.net/gwendal-leb...-stable/ubuntu).
The only other recent activity was installing MultiBootUSB which was quite problematic but installed through software center eventually. Also I added a new tertiary storage drive

[SuperFreak]

Any help would be gratefully received. I haven't had this problem for over a year and it has just cropped up again. I notice that Cinnamon has upgraded to version 2.02 recently but I think this occurred before the upgrade

freeze seems to occur randomly- in firefox in thunderbird

Installing MultiBootUSB it asked me to remove Thunderbird global menu and install a dependency for something else, I don't know if that is pertinent

[SuperFreak]

Anyone??