I’ve got it.
I have the same problem, in my case it seems that the method is thrown from background now (now in ios7, in ios6 UIAlertView was automatically put into the main-thread as @nodepond says -thanks!-)..
try to assure that the method is shown from main thread:
[alertView performSelectorOnMainThread:@selector(show) withObject:nil waitUntilDone:YES];
Good luck!