Why am I getting an EXC_ARITHMETIC error in iOS app?

My app is crashing and getting an EXC_ARITHMETIC error and I don't know why. Here is where the error is happening:

int main(int argc, char *argv[]) {

    NSAutoreleasePool * pool = [[NSAutoreleasePool alloc] init];
    int retVal = UIApplicationMain(argc, argv, nil, nil); //ERROR IS HERE
    [pool release];
    return retVal;
}

The error happens when I click a button in the app, it's hooked up in my ViewController.m file like this:

- (IBAction)btnPressed:(UIButton *)sender {
    [self btnPressed];
}

Which calls this code from the same file:

- (void)btnPressed {
    NSString *strInfo = [[NSString alloc] initWithString:@"Test Info. \r\n"];
    NSData *dataInfo = [strInfo dataUsingEncoding:NSUTF8StringEncoding];
    [strInfo release];
    [socket writeData:dataInfo withTimeout:-1 tag:1];
}

The btnPressed is also called when the app loads and it DOES NOT produce an error. As well if I add a breakpoint to the [self btnPressed]; line then when I click the button in the app it works, stops at the breakpoint and when I click 'continue program execution' it works without error as well.

Note: I'm using CocoaAsyncSocket to communicate with a Cocoa app.

This seems to be only a problem with iOS 5 sim, running fine in iOS 4.3.