WARNING: There is currently a problem that appears to be part of the Region-Crossing update. If an estate manager or other land owner bans and ejects a user, the region will crash when they leave the region. Oops!
It is currently unclear what the details are. Try ejecting without banning then ban. I have no idea if that will help.
The problem is related to https://jira.secondlife.com/browse/SEC-1204 and https://jira.secondlife.com/browse/SEC-1215. I can’t read the JIRA items in SEC, as most of us cannot. So, it is a pain getting details.
Some of the hinky details are in the Deploy thread: Deploys for 2013-01-28.