Grub Geom Error

Using GSX Server with Windows XP Pro installed. Everything configured and worked well for a week. I now get an error Grub geom error when starting Windows XP. Tried creating other VMs for Linux and other versions of Windows. With Linux I get Grub Hard Disk Error. I also get the same errors with Workstation. There have been no crashes or hangups of the system.

System

AMD Athlon 2100+

1Gig ram

80 Gig HD

K7s5a MB

Thanks

J