Network printer traffic is causing XP SEP clients to detect "UDP Flood Attacks" and blocking the traffic from the printer with the Intrusion Protection System (IPS)

This is a known defect with SEP11 RU5.

The correction for this defect is in SEP11 RU6 MP1, however Symantec recommends that any version upgrade be to SEP11 RU7 or SEP12.1.