Hello.
I have a serious problem. the only account that i can see in the memberlist is my admin account. All of the other members are gone. I looked in the DB and everything looks fine there.
When a user tries to logg on, they got the welcome messege and when they then press the proceed button they got redirected to the login page again.
Another problem i have is that all usergalleri pics and gone. i dont know if this is related in some way.
Check the users table in the DB still has the users and that your user groups are intact.
Posting a link might help.