If I start in safe mode I get a blank screen with safe mode in each corner, the Windows XP version centre top and nothing else. Stupidly I have not made a recovery disk, although I do have another machine (same make and model HP nc2400 running XP Pro) from which I could make a recovery disk if this would help. I do have the disk with the operating system. I also have a full backup of the affected machine.
Thanking you in anticipation.