Well, If for any one this helps.
The problem was with the iOS Framework. The problem was with UINavigationController's implementation. The crash was happening inside the framework itself. The only possible way out was to instantiate the Navigation Controller every time, before presenting it. This decreases performance, but had no other option. Apple, really does have a lot of limitations and assumptions. :P
Explanation: We needed to present a Navigation Controller with Modal animation. We were trying to avoid the instantiation of the navigation controller again and again by instantiating it once and trying to reuse it. However, because of this, we observed a crash happening sometime. Don't exactly know what the crash means, but fixed it by instantiating it again and again.