Sorry to everyone firstly, I originally thought that the disconnect issue was due to a malformed packet or incorrectly formatted packet, I now know this is not the case, if you kill 1 monster at a time, they will spawn 1 at a time. You do not get disconnected.
If you kill more then 1 at a time and they spawn, Boom... You're disconnected.
I now have this theory,
The server is saying 3 mobs have just spawned, and sends a packet for only 1 of these mobs, then the client crashed without an error... I will look into adding a Loop / While to send a packet for each monster spawn. =D Hopefully this would fix it!
//EDIT;
Guess what everyone... I have solved the problem of disconnecting when more then 1 monster is spawning.
It will be included in the next SVN deposit. (WOOHOO) Problem is, that when you use a skill that mass kills, I.E. scatter, each monster will die one by one at a speed of 100MS between them, you can see and hear it happen, but it's only really a nice looking light show ;)
FANTASTIC!!@
//EDIT 2;
Guess what, the newer and updated WorldHandler.CS file is now in the SVN Deposit. This file includes a temporary fix to the client crash when mobs spawn bug!
Wiki updated to include how to edit the fix to reduce it's wait effect.