TCP Communication Failing

We have just upgraded from groupwise 6.5 to 7. 3 Domains, 5 post offices,
and indexing agents. (Netware OES/ 6.5SP2)

The upgrdae went quite smoothly. However, we are now seeing something very odd.

ALl the links were using TCP. We are finding that they are dropping out.
(inter domain and domain to po) We change them to UNC and they start up
again. Change them back to IP and sometimes the links come up, other times
not. All ip addresses, ports have not changed since it was working
flawlessly on 6.5.

It has worked all night until about 10:00 this morning. The rest of onr
network is powering along without any problems.

Is anyone else seeing this?