iPhone crashing when presenting modal view controller

I have modified it slightly so that the loading view is shown after a tiny delay, and this works fine! So it appears to be something within the same event loop!

- (void)viewDidAppear:(BOOL)animated {
    [super viewDidAppear:animated];
    // Show load
    [self performSelector:@selector(doit) withObject:nil afterDelay:0.1];
}

- (void)doit {
    [self presentModalViewController:loader animated:YES];  
}