I have a windows nt4 server (PDC) that has exchange 5.5 (latest SP) and on
occasion (1 - 2 times per week) when I retutn to the office the server has
completly frozen.

There are not event logs produce and it always occurs @ 2200 (or there about)
and the only thing running is Backup exec.

As I already have mentioned this doesnt happen every day...

Server
PII 700
512Mb RAM
10/100 Network interface
SCSI hard disks