It looks like you may have a boot sector virus. A boot sector virus is one that infects the first sector, i.e.
the boot sector, of a floppy disk or hard drive. Boot sector viruses can also infect the MBR. All disks and hard drives are divided into small sectors. The first
sector is called the boot sector and contains the Master Boot Record
(MBR). The MBR contains the information concerning the location of
partitions on the drive and reading of the bootable operating system
When disinfecting a boot sector virus, the system should always be
booted from a known clean system disk. On a DOS-based PC, a bootable
system disk can be created on a clean system running the exact same
version of DOS as the infected PC. From a DOS prompt, type:
and press enter. This will copy the system files from the local hard drive (C:\) to the floppy drive (A:\).
If the disk has not been formatted, the use of FORMAT /S will
format the disk and transfer the necessary system files. On Windows
3.1x systems, the disk should be created as described above for
DOS-based PC's. On Windows 95/98/NT systems, click Start | Settings |
Control Panel | Add/Remove Programs and choose the Startup Disk tab.
Then click on "Create Disk". Windows 2000 users should insert the
Windows 2000 CD-ROM into the CD-ROM drive, click Start | Run and type
the name of the drive followed by bootdisk\makeboot a: and then click
OK. For example:
Follow the screen prompts to finish creating the bootable system
disk. In all cases, after the creation of the bootable system disk, the
disk should be write protected to avoid infection.
Once the OS loads, run your anti-virus software and it should clean the virus.
Should this not help, I'm afraid the only other alternative would be to reformat the HDD and reinstall XP again from a bootable disc.
Hope that helps..