Recently, when I was testing iAd app on iPad, I've got an error when accessing root view.
EXC_BAD_ACCESS code=2
Stack trace was looped infinitely.
We need to analyse the algorithm and change it to prevent call [self view] from error method of iAd delegate.
In my case it was easy:
During UI load my iAd banner already hidden.
I just check if banner is hidden and do nothing.
Here is a link to my post on stackoverflow - http://stackoverflow.com/questions/16471240/using-iads-on-ipad-crashes-after-huge-number-of-calls-to-bannerviewdidfailtorec/26025212#26025212