dismissModalViewControllerAnimated :(和dismissViewControllerAnimated）在iOS 5中崩溃

I can't find any logical explanation, but the fact remains that, in iOS 5 (xCode 4.2), if I presentModalView:* animated:YES, I can call dismissModalViewAnimated:* fine, but if I call presentModalView:* animated:NO, then calling the dismiss method crashes. (This works the same if I use the new presentViewController:animated:completion: + dismissViewControllerAnimated:). I am going TRY to work around this for now (I don't want the presentation animated) and report a bug to Apple, but I have been beating my head on this for a while. Any and all suggestions are welcome. Not much out there on iOS 5, so please help if you can. Sample code that does not crash in iOS 4 or iOS 5:I can't find any logical explanation, but the f