I have imaging set up and everything works fine. After a couple of days, I
can no longer connect a session either manually or through multicast. I
get three messages on the workstations trying to connect.

PXE-E32: TFTP open timeout
PXE-E32: TFTP open timeout
PXE-M0F: Exiting Broadcom PXE ROM

The only way that I have found to resolve the issue is to reboot the
imaging server. (I have tried restarting Zen, unloading/reloading TFTP and
PDHCP.) I checked my PDHCP.ini file, but it appears correct. Any help
would be appreciated

Zen 7 sp1 on Netware 6.5.