MyApp "has active assertions beyond permitted time" crash - CoreLocationRegistration and CoreLocationBackgroundClient

Does anyone have any insight on why this crash log is happening? The app records the locations where the user goes. So it has the UIBackgroundModes's Location is set in Info.plist to continue getting location updates in background. According to the log, something seems to crash after 10 minutes.

Incident Identifier: 4BA294E8-0DDF-4EC2-812A-20394F758A7F
CrashReporter Key:   59997a4e160853691bc673802439c8c4b9ca7ba3
Hardware Model:      iPhone3,1
Process:         MyMapApp [1234]
Path:            /var/mobile/Applications/826E35FE-F6B7-477E-943E-CE18D0D03145/MyMapApp.app/MyMapApp
Identifier:      MyMapApp
Version:         ??? (???)
Code Type:       ARM (Native)
Parent Process:  launchd [1]

Date/Time:       2011-03-02 13:25:05.228 -0600
OS Version:      iPhone OS 4.2.1 (8C148)
Report Version:  104

Exception Type:  00000020
Exception Codes: 0x8badf00d
Highlighted Thread:  0

Application Specific Information:
MyMapApp[1234] has active assertions beyond permitted time: 
{(
    <SBProcessAssertion: 0x63a07a0> identifier: CoreLocationRegistration process: MyMapApp[1234] permittedBackgroundDuration: 600.000000 reason: finishTask owner pid:1234 preventSuspend  preventIdleSleep ,
    <SBProcessAssertion: 0xa095050> identifier: CoreLocationBackgroundClient process: MyMapApp[1234] permittedBackgroundDuration: 600.000000 reason: finishTask owner pid:1234 preventSuspend  preventIdleSleep 
)}

Elapsed total CPU time (seconds): 43.660 (user 17.920, system 25.740), 7% CPU 
Elapsed application CPU time (seconds): 1.500, 0% CPU

Thread 0:
0   libSystem.B.dylib               0x33b5d268 mach_msg_trap + 20
1   libSystem.B.dylib               0x33b5f354 mach_msg + 44
2   CoreFoundation                  0x33a48648 __CFRunLoopServiceMachPort + 88
3   CoreFoundation                  0x33a47ed2 __CFRunLoopRun + 350
4   CoreFoundation                  0x33a47c80 CFRunLoopRunSpecific + 224
5   CoreFoundation                  0x33a47b88 CFRunLoopRunInMode + 52
6   GraphicsServices                0x33b0e4a4 GSEventRunModal + 108
7   GraphicsServices                0x33b0e550 GSEventRun + 56
8   UIKit                           0x32099322 -[UIApplication _run] + 406
9   UIKit                           0x32096e8c UIApplicationMain + 664
10  MyMapApp                    0x00105546 main (main.m:50)
11  MyMapApp                    0x00003f4c start + 44

Thread 1:
0   libSystem.B.dylib               0x33b89974 kevent + 24
1   libSystem.B.dylib               0x33c33704 _dispatch_mgr_invoke + 88
2   libSystem.B.dylib               0x33c33174 _dispatch_queue_invoke + 96
3   libSystem.B.dylib               0x33c32b98 _dispatch_worker_thread2 + 120
4   libSystem.开发者_开发知识库B.dylib               0x33bd724a _pthread_wqthread + 258
5   libSystem.B.dylib               0x33bcf970 start_wqthread + 0

Thread 2:
0   libSystem.B.dylib               0x33b5d268 mach_msg_trap + 20
1   libSystem.B.dylib               0x33b5f354 mach_msg + 44
2   CoreFoundation                  0x33a48648 __CFRunLoopServiceMachPort + 88
3   CoreFoundation                  0x33a47ed2 __CFRunLoopRun + 350
4   CoreFoundation                  0x33a47c80 CFRunLoopRunSpecific + 224
5   CoreFoundation                  0x33a47b88 CFRunLoopRunInMode + 52
6   WebCore                         0x304df124 RunWebThread(void*) + 332
7   libSystem.B.dylib               0x33bd6886 _pthread_start + 242
8   libSystem.B.dylib               0x33bcba88 thread_start + 0

Thread 3:
0   libSystem.B.dylib               0x33b5d268 mach_msg_trap + 20
1   libSystem.B.dylib               0x33b5f354 mach_msg + 44
2   CoreFoundation                  0x33a48648 __CFRunLoopServiceMachPort + 88
3   CoreFoundation                  0x33a47ed2 __CFRunLoopRun + 350
4   CoreFoundation                  0x33a47c80 CFRunLoopRunSpecific + 224
5   CoreFoundation                  0x33a47b88 CFRunLoopRunInMode + 52
6   Foundation                      0x336465f6 +[NSURLConnection(NSURLConnectionReallyInternal) _resourceLoadLoop:] + 206
7   Foundation                      0x33624192 -[NSThread main] + 38
8   Foundation                      0x3361d242 __NSThread__main__ + 966
9   libSystem.B.dylib               0x33bd6886 _pthread_start + 242
10  libSystem.B.dylib               0x33bcba88 thread_start + 0

Thread 4:
0   libSystem.B.dylib               0x33bd59f0 __semwait_signal + 24
1   libSystem.B.dylib               0x33b8a7ec _pthread_cond_wait + 748
2   libSystem.B.dylib               0x33b8a3d2 pthread_cond_wait + 26
3   CoreMedia                       0x31a41b14 WaitOnCondition + 4
4   CoreMedia                       0x31a41a5a FigSemaphoreWaitRelative + 66
5   MediaToolbox                    0x300c0c9c fpa_AsyncMovieControlThread + 48
6   CoreMedia                       0x31a5df76 figThreadMain + 166
7   libSystem.B.dylib               0x33bd6886 _pthread_start + 242
8   libSystem.B.dylib               0x33bcba88 thread_start + 0

Thread 5:
0   libSystem.B.dylib               0x33b8168c select$DARWIN_EXTSN + 20
1   CoreFoundation                  0x33a7f662 __CFSocketManager + 582
2   libSystem.B.dylib               0x33bd6886 _pthread_start + 242
3   libSystem.B.dylib               0x33bcba88 thread_start + 0

Thread 6:
0   libSystem.B.dylib               0x33b5d268 mach_msg_trap + 20
1   libSystem.B.dylib               0x33b5f354 mach_msg + 44
2   CoreFoundation                  0x33a48648 __CFRunLoopServiceMachPort + 88
3   CoreFoundation                  0x33a47ed2 __CFRunLoopRun + 350
4   CoreFoundation                  0x33a47c80 CFRunLoopRunSpecific + 224
5   CoreFoundation                  0x33a47b88 CFRunLoopRunInMode + 52
6   MapKit                          0x31be8906 TileCachePrivate::runCacheThread() + 274
7   MapKit                          0x31be87ea _runCacheThread(void*) + 2
8   libSystem.B.dylib               0x33bd6886 _pthread_start + 242
9   libSystem.B.dylib               0x33bcba88 thread_start + 0

Thread 7:
0   libSystem.B.dylib               0x33bd59f0 __semwait_signal + 24
1   libSystem.B.dylib               0x33b8a7ec _pthread_cond_wait + 748
2   libSystem.B.dylib               0x33b8a3d2 pthread_cond_wait + 26
3   QuartzCore                      0x3412e5dc CA::DispatchGroup::thread(void*) + 84
4   QuartzCore                      0x340fb01a thread_fun + 10
5   libSystem.B.dylib               0x33bd6886 _pthread_start + 242
6   libSystem.B.dylib               0x33bcba88 thread_start + 0

Thread 8:
0   libSystem.B.dylib               0x33b5d268 mach_msg_trap + 20
1   libSystem.B.dylib               0x33b5f354 mach_msg + 44
2   CoreFoundation                  0x33a48648 __CFRunLoopServiceMachPort + 88
3   CoreFoundation                  0x33a47ed2 __CFRunLoopRun + 350
4   CoreFoundation                  0x33a47c80 CFRunLoopRunSpecific + 224
5   CoreFoundation                  0x33a47b88 CFRunLoopRunInMode + 52
6   MapKit                          0x31bf327e +[NSThread(MKAdditions) _mapkit_runThread:] + 334
7   Foundation                      0x33624192 -[NSThread main] + 38
8   Foundation                      0x3361d242 __NSThread__main__ + 966
9   libSystem.B.dylib               0x33bd6886 _pthread_start + 242
10  libSystem.B.dylib               0x33bcba88 thread_start + 0

Thread 9:
0   libSystem.B.dylib               0x33b5d268 mach_msg_trap + 20
1   libSystem.B.dylib               0x33b5f354 mach_msg + 44
2   CoreFoundation                  0x33a48648 __CFRunLoopServiceMachPort + 88
3   CoreFoundation                  0x33a47ed2 __CFRunLoopRun + 350
4   CoreFoundation                  0x33a47c80 CFRunLoopRunSpecific + 224
5   CoreFoundation                  0x33a47b88 CFRunLoopRunInMode + 52
6   AudioToolbox                    0x316504ba GenericRunLoopThread::RunLoop() + 30
7   AudioToolbox                    0x31663306 TRunLoop<AQClient>::Entry(void*) + 90
8   AudioToolbox                    0x316501d2 CAPThread::Entry(CAPThread*) + 138
9   libSystem.B.dylib               0x33bd6886 _pthread_start + 242
10  libSystem.B.dylib               0x33bcba88 thread_start + 0

Unknown thread crashed with unknown flavor: 5, state_count: 1

Are you by any chance calling beginBackgroundTaskWithExpirationHandler: without calling a corresponding endBackgroundTask:?

http://developer.apple.com/library/ios/#documentation/iPhone/Conceptual/iPhoneOSProgrammingGuide/BackgroundExecution/BackgroundExecution.html