Since you have the XP cd now, I suggest you do the following:
Go to START-->RUN and type in cmd Then type in sfc /scannow <--Please note the space between sfc and /scannow.
You will be asked to put in your XP CD during this. This will check all windows files and make sure they are in their original format, replacing any that are not. Once the blue bar goes away, take out the XP CD and reboot your computer.
Once your computer is rebooted, put in your XP CD and then reboot your computer again. When the message comes up saying: press any key to boot from cd, press a key and windows setup will start. One the first screen that appears hit R to enter the Recovery Console. When asked which version of windows you want to login to, select 1 since that is the only version that will be listed. (If there is more then one, post in here and we will fix that.) Just hit enter when asked for the ADMINISTRATOR password because it is usually blank. Once at the C:\ prompt, type in the following:
chkdsk /p /r
This will check your hard drive for errors and fix any it finds. This will take awhile so be patient. Once it's done, type exit, take out the XP CD and let your computer reboot.