Got a phone call from mum yesterday saying the desktop wasn't coming up and it was stuck with a ring going round and making 'strange noises' I said LEAVE IT! Had a look when I got home and it was dead, nothing. Wouldn't come on... done a hard reset (first time I've had to do this) and it came up with various options etc. then I shut it down and tried turning it on again, came back fine! No errors and everything's been okay, any idea what can cause this!?