I have been facing some freezes in my desktop running Ubuntu 12.04 with the KDE desktop environment. The freezes occur randomly after few minutes in the session.

There is no keyboard input nor mouse during the freeze, however I can still connect remotely to it and browse files, I can even turn it off from a remote connection through my laptop.

Is there a way to find out what is causing this behavior in the Operating System in that desktop?

Power manager is set to never suspend / hibernate but after being away for a while I come back to a non responsive system.

I will appreciate all advices

How did you install KDE? You might have to uninstall it and do the following:

That will install KDE.

I'm not the expert here but Compiz could be to blame.

When I first installed Ubuntu 10.04 with Ultimate Ed I had to change my settings in Compiz several times to stop drop down menu's from crashing. And to stop graphics crashes-
I don't think it was my graphic's card.

The Ubuntu forum is a good place for info. about your system:
http://ubuntuforums.org

Not sure if this is your case but I'm trying to help-
Good luck

Thank you for the replies. I had installed Kubuntu back when it was 10.04 so I have been just upgrading this release is the one I have the most problems with. I dont think I have Compiz installed in this system. I have been considering just to switch distro but I have too many files to back up and lots of settings, applications and customizations to set up if I end up re installing so I would prefer no to do that.

I will appreciate more advices, thank you!