App crashes on i386, works on x86_64

I tried switching architectures in my Xcode project today, because I was about to use low level QuickTime stuff that's not yet ported to 64 bit yet. When i compiled before on x86_64 my app ran just fine. Then i switched the arch to i386 and boom, my app keeps crashing on startup.

The weird thing is, the stack tracke has nothing to do with my own code.

#0  0x9929ebf1 in __CFBasicHashDeallocate
#1  0x99286ea1 in _CFRelease
#2  0x992b397d in _CFAutoreleasePoolPop
#3  0x917d1dda in NSPopAutoreleasePool
#4  0x92b67bc9 in loadNib
#5  0x92b66f99 in +[NSBundle(NSNibLoading) _loadNibFile:nameTable:withZone:ownerBundle:]
#6  0x92b66eaa in +[NSBundle(NSNibLoading) loadNibFile:externalNameTable:withZone:]
#7  0x92开发者_StackOverflow社区b66df5 in +[NSBundle(NSNibLoading) loadNibNamed:owner:]
#8  0x92b63bf9 in NSApplicationMain
#9  0x000023c8 in main at main.m:13

Any ideas?

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My guess is that you have created objects in the nib that are not safe in 32 bit mode. You might, for instance, be making assumptions about the size of some object that is not true, for instance, using a double instead of a CGFloat or a int64_t instead of an NSInteger.