EXC_BAD_ACCESS (SIGSEGV) crash

How do I trace the crash ?

Process:         iAddressGrabber [253]
Path:            /Users/egrabber/Library/Application Support/iPhone Simulator/User/Applications/DB3B2896-258C-4EC2-A490-802B1190A675/iAddressGrabber.app/iAddressGrabber
Identifier:      iAddressGrabber
Version:         ??? (???)
Code Type:       X86 (Native)
Parent Process:  launchd [64]

Interval Since Last Report:          34544 sec
Crashes Since Last Report:           1
Per-App Interval Since Last Report:  0 sec
Per-App Crashes Since Last Report:   2

Date/Time:       2009-11-14 10:17:50.058 +0530
OS Version:      Mac OS X 10.5.8 (9L30)
Report Version:  6
Anonymous UUID:  3EC1BE31-C7B9-47B9-8056-879CC319BF57

Exception Type:  EXC_BAD_ACCESS (SIGSEGV)
Exception Codes: KERN_INVALID_ADDRESS at 0x00000000c0000023
Crashed Thread:  0

Application Specific Information:
iPhone Simulator 3.0 (138), iPhone OS 3.0 (7A341)

Thread 0 Crashed:
0   libobjc.A.dylib                 0x910e0688 objc_msgSend + 24
1   CFNetwork                       0x006b4868 URLConnectionClient::_clientDidFinishLoading(URLConnectionClient::ClientConnectionEventQueue*) + 194
2   CFNetwork                       0x006b40c8 URLConnectionClient::ClientConnectionEventQueue::processAllEventsAndConsumePayload(XConnectionEventInfo<XClientEvent, XClientEventParams>*, long) + 306
3   CFNetwork                       0x006b4d4c URLConnectionClient::processEvents() + 100
4   CFNetwork                       0x00662b29 MultiplexerSource::perform() + 183
5   CoreFoundation                  0x302452c1 CFRunLoopRunSpecific + 3217
6   CoreFoundation                  0x30244628 CFRunLoopRunInMode + 88
7   GraphicsServices                0x32044c31 GSEventRunModal + 217
8   GraphicsServices                0x32044cf6 GSEventRun + 115
9   UIKit                           0x309021ee UIApplicationMain + 1157
10  iAddressGrabber                 0x00001efc main + 102 (main.m:14)
11  iAddressGrabber                 0x00001e6a start + 54

Thread 1:
0   libSystem.B.dylib               0x928da286 mach_msg_trap + 10
1   libSystem.B.dylib               0x928e1a7c mach_msg + 72
2   CoreFoundation                  0x30244d62 CFRunLoopRunSpecific + 1842
3   CoreFoundation                  0x30244628 CFRunLoopRunInMode + 88
4   WebCore                         0x3588ea13 __ZL12RunWebThreadPv + 467
5   libSystem.B.dylib               0x9290b155 _pthread_start + 321
6   libSystem.B.dylib               0x9290b012 thread_start + 34

Thread 2:
0   libSystem.B.dylib               0x928da286 mach_msg_trap + 10
1   libSystem.B.dylib               0x928e1a7c mach_msg + 72
2   CoreFoundation                  0x30244d62 CFRunLoopRunSpecific + 1842
3   CoreFoundation                  0x30244628 CFRunLoopRunInMode + 88
4   Foundation                      0x3056002e +[NSURLConnection(NSURLConnectionReallyInternal) _resourceLoadLoop:] + 318
5   Foundation                      0x3050a79d -[NSThread main] + 45
6   Foundation                      0x3050a338 __NSThread__main__ + 280
7   libSystem.B.dylib               0x9290b155 _pthread_start + 321
8   libSystem.B.dylib               0x9290b012 thread_start + 34

Thread 3:
0   libSystem.B.dylib               0x929296fa select$DARWIN_EXTSN + 10
1   libSystem.B.dylib               0x9290b155 _pthread_start + 321
2   libSystem.B.dylib               0x9290b012 thread_start + 34

Thread 0 crashed with X86 Thread State (32-bit):
  eax: 0x00f797f0  ebx: 0x305063d1  ecx: 0x9117c334  edx: 0xc0000003
  edi: 0x00f7b3b0  esi: 0xbfffeaa4  ebp: 0xbfffea28  esp: 0xbfffe8a8
   ss: 0x0000001f  efl: 0x00010206  eip: 0x910e0688   cs: 0x00000017
   ds: 0x0000001f   es: 0x0000001f   fs: 0x00000000   gs: 0x00000037
  cr2: 0xc0000023

Enable NSZombie - it will tell you which de-allocated object objcMsgSend is trying to call.

See this earlier question.