Intermittant Network Failure

Last weekend we moved all of our servers into the new datacenter. One of the servers (the PDC/file server) has been suffering intermittant network outages since then. All the machines sit side by side and use the same switch and this is the only machine w ith this problem. We have tried switching network cards and cables with machines that work and have yet to isolate the problem. Incidentally, everything was a-ok in the old data center. We are using NT4/sp3 running at 100BT with 3com 3c597 network cards i nstalled in Compaq Proliant servers. Any ideas?

P.s. IP numbers were changed, but the switch is not overloaded. We checked.