Imap doesnt work anymore!!

Today I started to receive complaints of customers that cant access to their webmails.

I tried and it´s true, I cant access either. Looking at /var/log/messages i found this errors:

server1 httpd: IMAP toolkit crash: Lock when already locked, mbx={domain.com:143/imap/notls/user="info@domain.com"}IN

This error repeats with the respective account of each customer. Seems that something crashed.
I didnt any kind of cpanel update or httpd upgrade, everything was working fine and suddenly stopped.

I tried to restart imap, courier and httpd. And the error is still present.

Now I have to switch the webmail mode to pop3 to get it work again (Im using DWMAIL), but now sent folders are missing, cause they only work under imap.

Anyone had this issue and knows how to fix it?

Thanks!