Illegal Stance Exception

Hi,
I have some troubles with our server for some days now... I don't know exactly if it is a Minecraft related or bukkit related
One User causes the exception "Illegal Stance"

Code:

[WARNING] **** had an illegal stance: -7.117635623735635E11
[WARNING] **** moved wrongly!
[INFO] Got position 70.38636799872589, 46.12431008171874, 4.595231004651212E-305
[INFO] Expected 3.699999988079071, 68.5, 18.30000001192093

In many cases, this completly breaks down the server, after restarting, some chunks are rolled back and about 0-60 minutes of building are lost.
Has anyone experienced something like this? How can we solve it?

EDIT: by the way, I'm using the recommended build #531 and all plugins are working great, no errors at all.

Greetings,
Dawodo

 

same here. idk whats causing it tho but only one guy has it. anyone know?

 

I hear if you push someone off a bed this happens. Not sure if this still stands true or not.

 

This is a long-standing critical bug in MC, we have had many cases over time. 99% your culprit has or had ZoneAlarm installed.

http://www.buxville.net/showthread.php/7188-Illegal-stance-crashing

 

Yeah, there are many things you can do to get an illegal Stance Exception, we've tried many different things, but we dont get the server to shut down itself :/
However, thanks alot for the clue with ZoneAlarm! Will investigate that further...