virtualbox.org

Was working fine until recently and I am just looking for ideas of what to check:

XP Guest runs, but after a few minutes, the host drive locks up. XP continues to run fine as long as I don't click anything on the host screen, as the VDI is on another drive. I tried running fsck on both drives from another distro, I ran the windows check disk while running the host... and I can't figure out what is causing the issue.

This setup has worked for quite some time and just recently this has become an issue.

I cloned the VDI onto another removable drive, and it works fine from another Ubuntu Hardy machine.

I upgraded to the the latest VB package and this seems to have done nothing to solve the issue.

I think your hard drive is failing. Even though you check the drive with some disk check utitily from an OS, all that does is a data integrity and not a full mechanical test like the utility from the manufacturer. Please try their tool first, you might need to replace the drive.