Thank you for the tip bobw, I took it to my local Apple shop and they had a look and basically did all the tests that I had already done, then said the tech's had to look at it.
But 2 days later they gave it back with a new hard drive, sadly I lost about 30 gigs of work (which I know is my...
I was using my PowerBook G4 until it just froze for no apparent reason, so I turned it off and restarted it, it loaded into mac os x and then froze again.
Now when you boot it it normally stays on the grey screen with the apple logo and the spinning circle, if you leave it for about 20...