Cannot access escape menu.

When playing on some specific "servers" The operators are able to somehow DISABLE your escape menu. Whenever you try to access the escape menu it flashes and then is gone again. This is REALLY annoying to get around.

mc-cod.com
For example this bukkit server has this in place.
When in there tutorial they disable your escape menu.
I can see this being used for more nefarious purposes.

This bug inhibits a players ability to QUIT minecraft on there computer.

P.S. I came to the theory their server was accomplishing this by sending the clients computer a confirmation that they opened a chest or something thus making the games quit the escape menu.