[SLUG] linux grinding to a halt

[Christopher Booth (ATP) <christopher.booth@xxxxxxxxxxxxx>]

Sometimes (too often) I am working on my Mandrake 8.1 machine and suddenly everything grinds to a halt making me have to do a cold boot.
This is quite annoying and has the potential to corrupt data and losing information I am working on.
This happens sometimes when using Mozilla, or anything that is too processor or memory intensive.
I tried this morning to open a Compressed G4 multipage tif file in ee and it did it. I somehow got it back, I can't get to a virtual terminal by ALT F2, neither can I ALT Backspace, CTRL ALT DEL, ALT F4 or anything.  Keystrokes don't register. The mouse sometimes moves slowly.
I was logged in from another machine via ssh and that isn't responding either.

Anything I can do to stop this happening, I installed a monitor but it is practically useless :p

TIA

Chris