Dodgy RAM?

I've mentioned problems with my work laptop before (in conjunction with my 3G modem) but I'm beginning to suspect it might be hardware related.
The reason is that Ubuntu has just frozen up on me twice within half an hour. That's not something I've experienced before, and with the added problems of coming back from suspension or hibernation there must be something more fundamentally wrong with the laptop. I've had more problems with both windows and linux on this machine than on any other (well if we only count windows xp that is).
How I wish I had a mac right now...and before you ask: no I can't use my iBook as vmware wont run on a G4 processor.