Outlook 2000 Email Problem

[Jeff]

I have a couple of pc's that after a while start getting
erros that it cannot reach the email server. I restart
outlook and it starts working again then the cycle starts
repeating.

Testing, I set up the same account in outlook express 6.0
and run both programs at the same time. Outlook
continues to recieve errors while outlook express works
fine.

Does anyone know what may be happening?

Thanks