I have two apps that are in the app store with which a couple of users are having problems. They report that when they load the app it crashes several times but then they can load it. The curious part is that I have never seen this behavior. I have been testing the apps in 3.1.3 while the users have all been using iOS 4.
I suspect that it is a network timeout issue, but I cannot be sure since I cannot see their crash logs. An alternative might be a memory issue since 3.1.3 does not have multitasking while 4 does. Would many apps in background cause a crash (I have seen it slow an iPhone down.)
I wish I could provide some code but since I don't have the crashes I wouldn't know where to start looking. Does anyone have a suggestion as to what might be causing this?
First, why are you not testing on the current OS? Per Apple's guidelines (and good practice) you should be testing and building for the latest released SDK (currently iOS 4.2).
I would download the newest SDk if you haven't already and test your app in the Simulator. If that doesn't simulate the crash, then either upgrade your device to 4.2 or find someone who can test it on their device with 4.x installed.
You can post your applicationDidFinishLaunching method here and we'll see if we can help.
Also, you should be able to download crash reports from iTunes Connect. Hopefully, you archived your distribution build for symbolication.