This indicates an attempt to exploit a buffer-overflow vulnerability in a print provider installed by Novell Netware Client.
The vulnerability is in the nwspool.dll library's failure to properly handle overly long arguments to the EnumPrinters() and OpenPrinter() functions. A remote attacker may exploit this to execute arbitrary code.
Novell Netware Client 4.91
Novell Netware Client 4.91 SP1
Novell Netware Client 4.91 SP2
System compromise: Arbitrary code execution.
Apply the update issued by the vendor: