You really know how to describe a problem ...
What is your setup?
What version of CUCM, IMP, Jabber, ... are using?
Have you considered upgrading Jabber, if you don't use the latest version?
Is this happing to users in the internal network? Users connected via VPN? Or both?
What happens, when the user logs in again, after he was auto logged-out?
Have you checked the problem report? There is also a tool from Cisco, that analyzes the PRT for you https://cway.cisco.com/csa-new
What troubleshooting steps did you do already?
If you cannot describe your problem or cannot deliver answers, logs and debugs, nobody will be ever able to help you.
