Confirm that your hard disk or file system is not damaged.
Start your computer from the Windows XP CD-ROM, load Microsoft Recovery Console, and then use the Chkdsk command-line utility. This may solve your problem.
Important We recommend that advanced users or administrators use the Recovery Console. You have to know the Administrator's password to use the Recovery Console.
For additional information about how to check and repair a damaged hard disk by using Chkdsk, see the "Using the Recovery Console" and "Using the Recovery Console command prompt" sections in the following article:
307654 (http://support.microsoft.com/kb/307654/ ) How to install and use the Recovery Console in Windows XP
Note If the Chkdsk command reports that it cannot gain access to your hard disk, you may have a hardware failure. Examine all cable connections and any jumper settings on your drive. For more assistance, contact a computer repair professional or the manufacturer of your computer.
If the Chkdsk command reports that it cannot fix all hard disk problems, your file system or Master Boot Record (MBR) may be damaged or no longer accessible. Try appropriate Recovery Console commands such as Fixmbr and Fixboot, contact a data recovery service, or repartition and reformat your hard disk.
Important For more help, contact your computer manufacturer or a Microsoft Product Support Services professional.
Allow only qualified personnel to repair your computer. Computer repair that is performed by non-qualified personnel may nullify your computer's warranty.
If you repartition and reformat your hard disk, you lose all the information on the disk.
Source http://support.microsoft.com/kb/308041