My understanding is that this is a communications problem.
Originally Posted by freedaemons
More specifically than that I do not know.
The one fix that seems to work is to purge your ARP cache (on both your Mac and Router), most easily done by power-cycling both, making certain that the router is up and running before you power up the Mac.
Bill Magill - Mac Player - Old Timers Guild- Gladden:
Valamar: Dwarf Hunter - Level 100
Valdicta: Dwarf Rune-keeper - Level 100
Valanne: Beorning - Level 80