Suddenly unable to log into Exchange IMAP account

[Simon Brown <simon cliffestones demon co uk>]

Evening all

For some reason I can no longer log into an IMAP server I've been using 
for some sometime. It's the strathclyde uni mail server 
nemo.strath.ac.uk The password dialogue keeps popping up. I can however 
log into the same account using mutt so they haven't closed my account. 
It's an exchange server so I'm guessing it's been "upgraded" How do I 
generate useful debug info?

Simon