event log: not so informative

on my Win2k Terminal Server, when i check System Logs in Event Viewer. am seeing the follwing 3 different logs.

The printer could not be installed.

Printer security information for the printer /IBMWBT/Session 10 could not be set.

Driver required for printer is unknown. Contact the administrator to install the driver before you log in again.

now i want to know who is trying to install the printer on Terminal Services when i check for User field in log its mentioned as N/A whatdoes this mean & how do i trace if some users try to fiddle with server.