Yeah, Blizzard hasn't updated the World Editor for Mac since 1.21, and 1.24 breaks it. There's a partial fix so you can at least keep working without uninstalling 1.24 though; see my post here: http://www.thehelper.net/forums/showpost.php?p=1088628&postcount=31im on a mac if that make any different? and it saids there 4964 errors
Your probably using World editor unlimited.