This error will occur for a variety of reasons. A common cause is when going through portals and switching Alts (servers).
The error usually consists of the system locking up after going through a portal forcing you to exit the game. However when you re-enter an error box appears repeatedly called CMD.
The quickest way out of it instead of clicking on dozens of CMD errors is to right click on the DZ lobby and choose Close, then right Click on the Kingdom of Drakkar window and also click close. Wait for the "Program not responding" window and end the task. Then wait a minute or two and relaunch the game. This usually lets you back in without cramping your hand. If I find a real "fix" I'll post it.
Feel free to PM me in DZ (Civon) or IRC in #wolf is you have problems or questions.