Bugcheck and reboots

[Ayman Altounji]

All of a sudden today I'm getting reboots. In event viewr I have the following messages:

The computer has rebooted from a bugcheck.

The Compaq Management System Driver has detected that the system encountered an NT bugcheck during the previous Windows session.

This just started happening within today.
.
WinNT 4.0 service pack 6a. I use this server for email using Imail from ipswitch. Had a reboot/memory dump at 11:37, again at 2:12, and again at 2:45 today.

All quiet so far since.

Any reasons why all of a sudden this might be happening????

I have 2 other Prosignia 200 166 mhz operating in near identical setups and they have not encountered this so far.