imapd problems in 10.4.3

Hi !

I´ve recently installed an 10.4.3-server that only runs as a mail-server for about 120 users.
All runs fine but now some users cant login at all. Not from Mail with imap or via WebMail.

If I run a ‘ps aux | grep imapd’ on the server I can see that the user already have a process running but it is set to state ‘U’ which means that I cant kill that process in any way. The only way to recover is to restart the server.

The server have plenty of disk left, mailstores is on a separate partition and the problem is not isolated to any particular user or imap-subfolder.

So far I havent done much troubleshooting as I really dont know where to start… Could this be a hardwareproblem ? Never had a process been set to U-state before..

Br,
Daniel