Assigning a selector crashes on iPod touch 2nd generation

Question

Update: problem magically disappeared, see comment

I have a function which works fine on an iPhone 3G, iPhone 3Gs and simulator but crashes on an iPod touch 2nd generation.

- (id) initWithDelegate:(id) delegate
   data:(NSData *) data
                     finishSelector:(SEL)finishSelector{
 if(self = [super init]){
  _delegate = delegate;
  _finishSelector = finishSelector; // crashes

When it reaches the last line it crashes with “EXC_BAD_ACCESS”. When I put a breakpoint on that line and hover over finishSelector, I see this:

When I hover over _finishSelector I see this:

When I try "Print Description", the console returns:

Printing description of finishSelector:
The program being debugged was signaled while in a function called from GDB.
GDB has restored the context to what it was before the call.

The function is called like so:

 _teachersWordPlayer = [[SimplifiedPlayer alloc] initWithDelegate:self 
data:_audioFileService.responce
finishSelector:@selector(teachersAudioPlayerDidPlay:)];

Part of the header file looks like this:

@interface SimplifiedPlayer : NSObject <AVAudioPlayerDelegate> {
  AVAudioPlayer *_soundPlayer;
  id _delegate;
  SEL _finishSelector;
}
- (id) initWithDelegate:(id) delegate
   data:(NSData *) data
   finishSelector:(SEL)finishSelector;

I also tried to enable NSZombie, but it doesn't provide any more details about the crash (I don't expect it to, because I never released _finishedSelector afaik).

Can anyone tell me what's going on, how to fix this and/or how to find out what's going on?