Outlook not downloading email

I've always been able to receive my comcast email via Outlook Express. However, without making any changes, my email for one of four ofmy accounts won't download. I have to check it manually using comcast's website. Anyone know how this happen and/or how it can be fixed?

Have you already tried the Comcast FAQ here?...

http://faq.comcast.net/faq/query.jsp?name=Email#Outlook_Express