I have some problems running XCode 3.1.3 I have actually had Interface Builder working (But not now). I think it is related to having tried to force install of higher versions? (So I could try to remove or downgrade something). Or that I cleaned up a bit to much? From:
/Developer1.3/Applications/Interface Builder.app/Contents/MacOS:
dyld: Symbol not found: __NSConcreteGlobalBlock Referenced from: /System/Library/PrivateFrameworks/CoreSymbolication.framework/Versions/A/CoreSymbolication Expected in: /usr/lib/libSystem.B.dylib