I have had the same problem on a couple of computers at work. The problem was a (maybe misformatted) mail. When I deleted it, Outllok Express worked as it should again. Luckily the offending messages were spam...

So you could try to telnet in to the pop-server and check the first mail. If it isn't anything important, delete it and try again. If it is important, cut and paste the important bits, then delete it and try again....

Stig