As a followup to my former problem, it seems that Radiant does save a (workable and openable) file if I choose the .xmap save option. (btw, adding .map to the end of the name did not work) What is the difference between .xmap and .map files, and why are the saves so small (10kb)? I dont think that my version of Radiant is corrupted in some way, because I redownloaded the app and got the same problem.

Also, I am not sure if I should post problems with Radiant in the editing section or the nexuiz support section (which seems to deal more with ingame issues)...

-Torus

Have you opened the file in a text editor? .map files are human readable and a whole load of coordinates. If the file is seemingly gibberish then it could mean that it is a compressed file. Have you got it set to the right game? Nexuiz will take Quake 1 or 3 maps, both of which have a source file called .map but they are slightly different inside.