|Thanks for the replies.|
Had a virus attack which Nortons seemed to prevent, however the next time I rebooted, by PC went into a cyclic reboot!
I tried to do Windows XP install repair, but no change. I then tried complete re-installation of Windows XP. On reboot gets to windows logo and then just hangs. Left it in this state for 12 hours, no change!
Installed Ubuntu and PC seems to work fine, but cannot get windows to work!
Last resort is to try reflash the bios???