Pre-crash iphone symptoms - odd user position, volume change

I'm seeing intermittent strange symptoms in my app:

1. Blue blob (user position in MKMapView) starts "exploding" (odd, jerky animation). Can begin at startup and seems to indicate eventual problems.
2. Speaker volume suddenly increases (back to level before I invoked kAudioSessionSetProperty_OtherMixableAudioShouldDuck). The app ke开发者_运维问答eps running, but this change tells me to expect no more sounds from AVAudioPlayer. Also a reliable indicator of a future crash (on save, etc).

I'm having trouble provoking this in the debugger (seems to only happen with movement in GPS). Any ideas to track it down?

One possibility: could slow code (only executed when moving) cause the problem?

This symptom (odd blinking blue user location) appears to be caused by memory corruption.

Tracked it to usage of

self.audioPlayer = nil

instead of

[audioPlayer release];