My iphone application crashes

I made an application that should run constant until I stop it. What it basically does is getting some data from connected another device and send that data to the server periodically using NSURLConnection, and read data from the server periodically and visualize that data as a graph using NSXMLParser.

I ran the instrument to check allocs and leaks. No leak at all. memory monitor shows consistent 5.2MB. Objectalloc graph is stable, Net bytes of objectallo is arouend 480000 and #net is around 6400.

The problem is the application is stopped (or crashes) about 12 hours later. What are possible problems? I have absolutely no idea where to start finding the problem because neither a debugger nor the instrument don't show any error or problem.

[added]

1 . as Paul's suggestion, I ran my app on the simulator and got some error messages after 5 hours of running.

InAir(64628,0xa050c720) malloc: *** error for object 0xc015bc87: Non-aligned pointer being freed
*** set a breakpoint in malloc_error_break to debug
InAir(64628,0xa050c720) malloc: *** error for object 0xa0200100: pointer being freed was not allocated
InAir(64628,0xa050c720) malloc: *** error for object 0x2080a043: pointer being freed was not allocated
InAir(64628,0xa050c720) malloc: *** error for object 0x120100: pointer being freed was not allocated
InAir(64628,0xa050c720) malloc: *** error for object 0x34a00000: pointer being freed was not allocated
InAir(64628,0xa050c720) malloc: *** error for object 0xc1d3a1b1: pointer being freed was not allocated
InAir(64628,0xa050c720) malloc: *** error for object 0x46b0a1b1: pointer being freed was not allocated
InAir(64628,0xa050c720) malloc: *** error for object 0xc1d3a1b1: pointer being freed was not allocated
Program received signal:  “EXC_BAD_ACCESS”.

2 . About NilObject's comment... I didn't know the organizer has crashlog. Yes it has.

Incident Identifier: 0ADC2722-BF4B-457F-A224-4A946810FB1F
CrashReporter Key:   f62c1dc12071b63c1e21d612962ee6aad74b4503
Process:         InAir [3154]
Path:            /var/mobile/Applications/9471A5CA-97E1-4E52-A934-9CE33DC5A5DB/InAir.app/InAir
Identifier:      InAir
Version:         ??? (???)
Code Type:       ARM (Native)
Parent Process:  launchd [1]

Date/Time:       2009-02-21 21:37:36.786 -0500
OS Version:      iPhone OS 2.2.1 (5H11a)
Report Version:  103

Exception Type:  EXC_BREAKPOINT (SIGTRAP)
Exception Codes: 0x00000001, 0xe7ffdefe
Crashed Thread:  0

Thread 0 Crashed:
0   libobjc.A.dylib                 0x300c8c18 objc_msgSend + 20
1   InAir                           0x00003d34 0x1000 + 11572
2   Foundation                      0x306942a0 __NSFireTimer + 132
3   CoreFoundation                  0x30269d88 CFRunLoopRunSpecific + 2642
4   CoreFoundation                  0x30269320 CFRunLoopRunInMode + 44
5   GraphicsServices                0x31567e58 GSEventRunModal + 268
6   UIKit                           0x30a4fa6c -[UIApplication _run] + 520
7   UIKit                           0x30a591d0 UIApplicationMain + 1132
8   InAir                           0x000020b6 0x1000 + 4278
9   InAir                           0x0000202c 0x1000 + 4140 

Thread 0 crashed with ARM Thread State:
    r0: 0x0013b920    r1: 0x301a2410      r2: 0x0013b920      r3: 0x301a2410
    r4: 0xc004ea47    r5: 0x001203d0      r6: 0x001203d0      r7: 0x2fffef50
    r8: 0x001203d0    r9: 0x394346d0     r10: 0x001063b0     r11: 0x00000f03
    ip: 0x0000a134    sp: 0x2fffeef8      lr: 0x00003d3b      pc: 0x300c8c18
  cpsr: 0x00000010

(etc... The entire log is here. )

Anybody who can interpret these?

Have you tried to set a breakpoint on malloc_error_break as the error messages tell you? (Run → Manage Breakpoints → Add Symbolic Breakpoint).