Ive got a COMPAQ AMD-64 laptop now running Ubuntu 12.04 using compiz because of its graphics card capabilities. It locks up periodically, unable to ctrl alt f1 into a tty (the mouse moves around though). There isn't a fix because the problem is compiz as I understand it, which is required by Unity. I'm beginning to get use to it and hate to uninstall it now.
But I can't do any serious work with my laptop now with Ubuntu 12.04 on it, but its great for running Firefox, Chromium and Thunderbird.. for reading only. I've been burnt with losing data in LibreOffice.
On the other hand, Ubuntu 10.04 is ROCK SOLID. Ubuntu 10.04 absolutely never gets in a total freeze. If an application does lock, I can always open a terminal and resolve it.
I'd like to keep Ubuntu 12.04 of this laptop if I could install some tool that resets the lock, and saves my data. Is there such a thing?
Otherwise, I'm going to install Xubuntu or Ubuntu 10.04 for stability and productivity.
IMO, if compiz is indeed the culprit, then I have to say it was a mistake to ever design an operating system that depends upon it. No one serious about doing work could consider using it. It'd be better off for Canonical if the user gets a message that says "incompatible with Unity" than the user installs a system that seems to work great... most of the time. Once lose data due to lock ups, they aren't going to be able to depend upon it.