I've tried this with the order you gave above and it worked as it should - the client disconnected and the other client received the quit correctly, no more commands could be sent to the server.
The only other results I can get out of this is with the conditions I mentioned in my last post.
I spoke to qwerty online about it and he couldn't reproduce it either...both using mIRC 6.14. I think it's most likely either 1) Lag, 2) Screen freeze or 3) Some sort of script.
Regards,
