Hi,

I have been using linux for a while, but the PC I have currently, no matter what distribution I use it seems to work fine for a while but it gets strange errors (particularly in the gui).

Multiple applications develop segfaults, and require reinstalling, the window manager crashes, the screen goes black, programs crash/wont load. This happens on both kde and gnome.

Sometimes a restart (or two) fixes all problems and I can run it for days (it still eventually crashes), sometimes updates fix it, but I don't know how to diagnose what is happening.

How can I find out if it is a hardware or software problem, and then what part?

I am currently running Kubuntu with the NVidia drivers (NVIDIA 280.13) on an AMD Athlon(tm) II X4 640 Processor with a 64bit kernel and an asrock n68-s3 motherboard.

From the symptoms you describe it is almost certainly a hardware problem and it will be difficult to diagnose unless you have access to a stock of "known good" similar replacement parts to progressively swap. The power supply and memory would be good to start with because they are easy to change. If you have more than one memory module you could simply try removing each one in turn. If you have any non-essential devices you could remove them

A lot of installation disks offer a memory check in their start-up menu. I can't remember if Kubuntu does, but that's a good place to start.

Ksensors or the CLI tool sensors will check on the various voltages and temperatures:
http://www.informationweek.com/news/...tech/229217825