Cannot Use Network or Load ZoneAlarm

On one of my Windows 2000 Servers, networking seems to be in a corrupt
state. It works upon booting, but then within maybe 20 minutes it cycles
for periods of one or two hours between working and not working. What is
interesting is that only certain kinds of TCP access fails. Local
connections work. Access to the Internet through our proxy server fails
(we use winsock on this machine). On other identical machines,
everything works perfectly during the periods when networking fails on this
one machine.

The event viewer doesn't contain anything very obvious, but one possible
clue is that ZoneAlarm is refusing to load with what appears to be a
permission problem:

"TrueVector driver: Driver install or load failure: LoadNTDeviceDriver.
Win32 error: Access is denied."

What resource needs to have what permission for a device driver to load into
Windows 2000? Where would I check to make sure this resource has not had
its permssions downgraded?

Any other things I should be checking or trying out to recover?

--
Will
westes AT earthbroadcast.com