sleep issue after Security update 2006-02

Since after updating with the Security update 2006-02, my Mac would immediately wake up right after going into sleep mode (both maunal or timed). I have found out in the System logs, AppleTalk shutdown and startup triggering the wakeup signal. In my Network preference, I have the AppleTalk enabled as well as in the Energy Saver Wake Option: "Wake for Enthernet network administration access" enabled. If I disable the latter option, the sleep would work properly. Not sure why the sleep mode behaviour has changed from before applying the security update, since this option has been default as far as I remember I had my Mac and Mac OS X.

Power Mac G4 (QuickSilver) Mac OS X (10.4.5)