Norton Internet Security block Outlook incoming mail

In the last 6 weeks I have had 3 computers in my office stop receiving emails in Outlook because of Norton Internet Security.  All 3 systems are Windows 7 Pro computers.  If I reboot, there is a small window in the beginning when emails will come in.  After receiving a batch of emails the incoming emails get blocked.  If I remove Norton Internet Security, everything works fine.  Please help with any suggestions.