I've been finding that if I include a ? in the map name upon creating a map, the map editor locks the game up and becomes completely unresponsive. I don't know if it has been mentioned before, and I guess it's an easy thing to "not include question marks in map names", but I thought I'd mention it anyway.
Here is the picture of what I see upon creating a map with a ? in the name:
Spoiler
(http://i.imgur.com/uov5wmd.jpg)
From Virgil's todo list (http://knucklecracker.com/forums/index.php?topic=21687.0)
Quote
Disallow characters in map names that are illegal to use in file names.
Same thing happened to me. Just only put letters and numbers in