Xcode Error - Command /Developer/usr/bin/momc failed with exit code 6

I am trying to build an app, but seem to run in the following error. Not sure what is wrong because it works properly for other builds. I saw that someone had a similar issue, but he fixed it and there was no solution for it.

2011-05-18 14:00:47.642 momc[296:607] *** Terminating app due to uncaught exception 'NSInvalidArgumentException', reason: '*** -[NSKeyedUnarchiver in开发者_如何学JAVAitForReadingWithData:]: incomprehensible archive (0x62, 0x70, 0x6c, 0x69, 0x73, 0x74, 0x30, 0x30)'
*** Call stack at first throw:
(
    0   CoreFoundation                      0x00007fff869057b4 __exceptionPreprocess + 180
    1   libobjc.A.dylib                     0x00007fff803890f3 objc_exception_throw + 45
    2   CoreFoundation                      0x00007fff869055d7 +[NSException raise:format:arguments:] + 103
    3   CoreFoundation                      0x00007fff86905564 +[NSException raise:format:] + 148
    4   Foundation                          0x00007fff83e6ee4f -[NSKeyedUnarchiver initForReadingWithData:] + 2970
    5   Foundation                          0x00007fff83eaa873 +[NSKeyedUnarchiver unarchiveObjectWithFile:] + 132
    6   momc                                0x000000010000122c 0x0 + 4294971948
    7   momc                                0x00000001000017cd 0x0 + 4294973389
    8   momc                                0x0000000100001e8c 0x0 + 4294975116
    9   momc                                0x0000000100000de4 0x0 + 4294970852
    10  ???                                 0x0000000000000004 0x0 + 4
)
terminate called after throwing an instance of 'NSException'
Command /Developer/usr/bin/momc failed with exit code 6