FYI, I was getting this error, and it had to do with the UIImageView's Highlighted property being set through Interface Builder. It was crashing the app right away. Hope this can help folks.
2010-10-18 16:35:23.908 myapp[5771:207] *** Terminating app due to uncaught exception 'NSInvalidUnarchiveOperationException', reason: '*** -[NSKeyedUnarchiver decodeBoolForKey:]: value for key (UIHighlighted) is not a boolean'
*** Call stack at first throw: