Recently I took my 120GB NTFS drive to my brother's
house. He connected it to his computer, booted up and
imported the drive using "import foreign disk". It came
up and he was able to copy files. When I brought the
drive back to my computer (where it originally came
from), it would not reactive or import.

I then downloaded a program from Runtime(.org) called
System Info and it stated the drive was a "(Secure File
System (Peter Gutmann))" not an NTFS. Well, I managed to
find out there is a single byte in the partition record
that tells what type of partition it is. Mine had somehow
become the Secure File System (42h) instead of NTFS
(07h). I took the drive to a friend's house and he used
DiskExplorer by Acronis and edited that one byte. After
two reboots, the drive was back to normal. I double-
checked my other drives and one other drive was
configured this way as well, but showed no problems. I
fixed it anyway without any problems.

My question is this, does anyone know how or why that
byte changed? Has anyone run across this problem before?
Could it be a virus that no one has heard of yet (I
checked)? Thanks for any light that can be shed on this.