I bought all of the bits n bobs to put together a new PC, chucked them together
I'd be happier to read "installed carefully, using anti-static strap and making sure all connectors were cleanly seated and nothing touched things they shouldn't".
Seriously, if you didn't use anti-static precautions while installing CPU and memory in particular I'd worry about b*****ing those. If the CPU fails you probably won't get it to boot at all, but corrupted memory can cause all sorts of weird errors that look like different problems entirely. I'd run Mtest86 for several (say 4) passes before clearing the memory of suspicion. That will take a few hours no matter what the speed of CPU, memory or buses.
So, I installed Ubuntu on the first hard disc and got it up and running, apparently stable although I can't actually set anything up to leave it doing something.
Do you mean it won't stay running with no-one logged in? Or it crashes every 5 minutes, or what?
I ran the memory test from the Ubuntu startup screen and it chugged all of the way through the mmemory with no errors. Then I enabled the networks and wireless driver (all point and click stuff) and got it to connect to our wireless router and the WWW and started to surf and find that it crashes, often, and re-boots and then offers to send an error log to somewhere.
If it crashes in much the same way every time it could be corrupted memory or corrupted disk. I have also had a machine (the one I'm typing on now actually) crash like that thanks to a spider's web and the dust it collected on the back of the motherboard, this shouldn't be your problem today though.
The error appears to related to a file called ooops. Is there anything in the error log, if I can find it, which will help me to find out why the crashes happen?
A crash of this sort doesn't have time to get into the logs. If you want to try, they are stored in /var/log -- you can ignore the ones with names ending in .gz although "zmore <filename>" will show them. The others will have the most recent boot at the bottom, so you may need to flick through the whole thing to find messages timestamped around the time of your crash. If the whole shebang just keels over in a flash don't hold out much hope though.
'b