<<I know I am sounding dumb here, but I do have an XP CD, I can change to boot from there by switching the drive in set up, but how to I run a disk diagnostic?>>
You are not sounding dumb, it's me who's being dumb
. Because I have had two desktops available for so long, I seem to think that everyone has a spare computer...if one is not working, the other will. My apologies
Since you have an XP CD...a slight change of plan will do. Rather than run a disk diagnostic, we'll see if chkdsk will run to completion on the drive.
To run chkdsk /r, still need to change the boot option in Setup/BIOS so that the CD/DVD drive is the first boot option. Save the changes by hitting F10...the BIOS will close and XP will reboot. The XP CD should already be in your CD/DVD drive.
WIndows XP will start to load. Eventually you will be prompted to select between Setup Windows and Repair Windows.
Hit 'R' for Repair Windows.
The RC (Recovery Console) will look for existing Windows XP installs to repair. Usually you have just the one, listed by the RC after it has scanned your disk, so type '1', then hit ENTER. If the RC doesn't find any Windows Installs...you're in trouble.
Usually your admin password is blank, so just hit ENTER when prompted for a password.
Type chkdsk /r, exactly as shown...with a space between the k and /. This command will start the XP repair/maintenance tool. If the hard drive is very large and/or has problems...it may take some time for it to complete. When it does complete, it will go back to the line where you typed the chkdsk /r command.
If the CHKDSK finally succeeds without errors, then you merely type EXIT, hit ENTER. System will reboot.
If chkdsk encounters any problems, it will provide error messages. Please write such down if they occur.
That's enough for now
. Post back.