Well as it's been working fine for a month I would suggest you get in touch with tech support to test your connection out. If you don't want to spend hours on the phone to telephone support, you could always try VM's newsgroup support. They are very helpful and normally you get a reply quickly.
For how to setup outlook express for newsgroups:
http://www.virginmedia.com/customers...setting-up.php
and the group you need to subscribe to is:
virginmedia.support.broadband.cable
Post on the above newsgroup with a description of your problems and see what they're got to say on the matter.