In my case all I wanted is to be able to get inside VSS 6.0 Admin. I
renamed the original um.dat to um.dat.orig and copied a um.dat that
came with a fresh VSS install which only had the admin and guest users.
User admin had an empty password.

After that I was able to easily create the users from the users.txt
file, which I had backed up earlier.

I hope this is a quick solution rather than having to go through other
complicated processes.

Thanks

Narayanan Sankaranarayanan