Forum Users can't login - started yesterday
 

We have users who can not login, i does not help if we resets their passwords in admincp.
The "send new password" function isn't helping either.
We have upgraded the forum to the latest patch level 4.0.2 PL4 about 1 week ago.

The problem started all suddenly and now we are experiencing huge problems.
The problems are very similar to those in this thread
http://www.vbulletin.com/forum/showthread.php?344532-suddenly-a-ton-of-users-can-t-login

Any ideas?