I then started it back up again but while the computer was working (and the computer fan was continuosly going), i just got a blank screen. I manually shut it down again. I left it a few mintues and tried starting it up. This time it went all the way to the blue "Welcome to Windows" splash screen - but it went no further.
Now when ever i try and start it up, the computer runs with the fan on continuosly but the screen is blank and showing no sign of life.
The PC is a HP Pavillion A708.UK (about 3yr old)
The spec is;
Windows XP SP2
Intel Celeron 4.3 Ghz
80 GB HDD
Nvidia Geforce MX4000 128MB
Any help much appreciated.