Single hotmail user doesn't stay connected

We’re using Openfire 3.6.0a and IM Gateway 1.2.4d under windows 2000 server with approx 10 users on spark 2.5.8

Today I have one user who cannot stay connected to MSN, the openfire connection is fine and he can talk to internal staff, but he after the MSN connection is made he is imediately shown as offline to other MSN users (although to him it looks like he is online). He cannot raise conversations etc…

This seems to be isolated to this one user, (he has a address if that matters, none of the other users do), so I am guessing it’s something to do with his login.

Before I start looking at debug logs etc, can anybody suggest anything obvious this might be ?