You should not stop Defrag mid flow, this has probably caused a bit of file corruption.
You need to use an XP disc, if that is what you have, a Recovery disk from the PC manufacturer will not work.
If you have an XP disk then follow this:
Put the disk in the CD drive when the PC is powered on and then reboot it.
Follow the prompts until you get an option for the Recovery Console. Press R on the keyboard and Enter.
At that c: prompt, type chkdsk /r
exactly as written here with the gap before the slash, then hit Enter.
2.You will then see a message "Would you like to schedule this volume to be checked the next time the system restarts? (Y/N)"
Type Y for yes, and press enter. Then reboot the computer into normal mode. Chkdsk will start when Windows begins loading again. Let all 5 phases run and don't use or turn off the computer. (The chkdsk process may take an hour or more to finish and may appear to freeze which is normal.)
3.Chkdsk finds any corrupted files that are causing the problem and fixes them. Read the results of each phase as it finishes. During the final phase, it will notify you if it finds any corrupted files. It also checks for bad blocks on the drive surface.
4.When the Check Disk is done, it will finish loading Windows.
If the XP disc does not boot and it goes straight to the Blue screen you will first have to boot into the Bios and change the boot order, so the CD drive is in 1st position.
Let us know what happens.EDIT
Sorry my post crossed with Allan's, but the additional instructions may help.
Edited by mark1956, 24 January 2012 - 05:33 PM.