Screen turns black?

[Man-o-Bomb]

When someone leaves my map, the screen of the player turns black and has to close hes warcraft 3... Why?

 

[Romek]

When someone leaves a map, Warcraft clears the memory that map was using.
If your map leaks a LOT, then that black screen will stay on for quite a while.

Reading a leak tutorial will probably help. It'll also fix the lag your map is probably having.