If you convert your maps from QuArK through Doom 3 Editor, DarkRadiant might crash on a couple of things. If this annoys you, you'll need to copy and paste each world brush into another *Radiant, saving after each brush copied. Its because the map wasn't converted all the way, and the other *Radiant editors don't recognize the format, but will convert one brush at a time. To make it the copy and paste faster, comment out the assertions from GtkRadiant sourcecode. I submitted a bug to NetRadiant, and I'll give one to GtkRadiant too.