when in Safe mode? I will suggest a software anomaly (infection) if so.
Windows XP home cannot find 2nd hard drive, it does not show up in disk management. It does show up in the bios.
At one point it did show up, healthy formatted NTFS drive.I was able to add a file after that it was gone.
I have one user account, and GUEST account.
I checked permissions and set them all to enable.
I don't know what else to do.