Sounds like the "permissions" changed. Check to see that you, the "owner" have read / write / execute permission on the folders:
_vti_pvt and web.roster.htm
and the contained files:
service.cnf and tmp respectively.
If that's not it I can't help you. Never used FP2000. I'd suggest asking your 'provider' which I guess is your "webspace provider/host" to fix it or look for a new one...
Edited to add: I'm not a ( network guru ) or any other kind of guru for that matter, just had a few websites over the years... good luck.
