The files were deleted but the users still exists. The folders were empty.
It seems to me that there is something wrong with Norton File Saver. I've just found two files called "Norton FS Data" and "Norton FS Volume" which were modified just before the crash.

Is there a folder in youur Users folder callled "deleted users" by any lucky chance?

Those invisible files, I recall from OS 9 days, were the backup directory information files that UnErase needed.

Just a thought--if you boot into OS 9 you should be able look at all the files without interference from the OSX permissions.

I booted on OS 9 just after I saw that my files were deleted, and I couldn't find anything.
There was no "deleted users".