It sounds like a hard drive problem. Try running chkdsk from the Recovery Console.
You are going to have to get into BIOS Setup on your computer to set the CD/DVD drive as the first bootable device, so you can then boot your XP CD, unless it provides the ability to press a Fn key at boot time to bring up the boot selection menu. If it does, use that.
How you do this varies with each manufacturer. Normally you press F1, F2, F10 or Del when you see the manufacturers logo. Often there is a clue somewhere on the screen when you boot normally telling you what key to press. Some computers (most newer ones) have a key you can press (often F12) to bring up the Boot Menu from where you can select the CD/DVD drive to boot from.
Boot the CD and at the first opportunity, enter R
to start the Recovery Console.
Next, choose which XP installation you want to login to. Normally this will be 1.
Lastly you will be asked for the Administrator password. Just press the Enter key as the Administrator does not have a password (unless you gave it one, then you would enter it).
From the command prompt, type: chkdsk /r
and press Enter
Allow it to complete undisturbed. It can take an hour or more depending on the size of the hard drive.
Remove the CD, type exit and the computer will reboot. Hopefully that will have fixed the problem (corrupted file system).
You may have to try the Repair again. If that doesn't work then you will have to do a Clean Install formatting the hard drive during the installation process so save your data first as it will be lost other wise. An easy way to do that is to boot a Live Linux CD (or flash drive if your computer supports it) like Linux Mint Mate, which is very "Windows" like. See here: Emergency Kit - save your files from a dead OS