I would ask your server how to correct it. If they know that it is an Outlook Express problem, they will know how to solve it.
I personally do not see how it could be an Outlook Express problem. I would suspect the server, your internet provider, your internet connection, or your router.
I often have problems with my router where it will periodically cause timeouts on the internet. If you unplug the router's power cord and then plug it back in, that usually corrects that. Maybe that is your problem. It is worth a try.