I'm running windows XP Professional with 1.25gb ram and a 120gb harddrive.
I've noticed that recently outlook express seems to hang everytime it tries to receive e-mail from the ntlworld server. Note that this occurs halfway through receiving email and is usually sutkc on a specific message e.g. message 58 of 69.
This could be the buffer at your ISP's end, it does tend to happen sometimes when you receive a lot of mails. Try downloading the freeware from Mailwasher, mind you this sometimes happens with also, but only for a couple of seconds.