App crashes on iOS5 simulator and on profiler-Collection of common programming errors

My app crashes on the iOS 5 iPad simulator after about 5 min of smooth running. This is the only crash reference I get from Xcode, when I try to do a profile run using zombies/memory leak, the app for some reason won’t even load (splash-screen shows and then the app crashes), I have no clue what is causing this behavior, any ideas?

error: memory read failed for 0x0

More info: I use ARC, the app works well on iOS6 & iOS7