我正在使用Facebook SDK打开一个对话框，用户可以使用该对话框在另一个用户的Facebook时间轴上发表评论。有时应用程序在打开Facebook对话框的确切位置崩溃。崩溃日志的片段：
Date/Time: 2012-03-19 16:33:00.053 +0000
OS Version: iPhone OS 5.1 (9B176)
Report Version: 104
Exception Type: EXC_BAD_ACCESS (SIGSEGV)
Exception Codes: KERN_INVALID_ADDRESS at 0x00000008
Crashed Thread: 2
Thread 2 name: WebThread
Thread 2 Crashed:
0 WebCore 0x3248578a WebCore::FrameLoader::interruptionForPolicyChangeError(WebCore::ResourceRequest const&) const + 2
1 WebCore 0x326f1e98 WebCore::MainResourceLoader::stopLoadingForPolicyChange() + 20
2 WebCore 0x322f9200 WebCore::MainResourceLoader::callContinueAfterNavigationPolicy(void*, WebCore::ResourceRequest const&, WTF::PassRefPtr<WebCore::FormState>, bool) + 8
3 WebCore 0x321d07ec WebCore::PolicyCallback::cancel() + 48
4 WebCore 0x321d0326 WebCore::PolicyChecker::stopCheck() + 38
5 WebCore 0x321d219a WebCore::FrameLoader::stopAllLoaders(WebCore::ClearProvisionalItemPolicy) + 34
6 WebCore 0x322f0986 WebCore::FrameLoader::detachFromParent() + 90
7 WebKit 0x31b0ad0c __-[WebView(WebPrivate) _close]_block_invoke_7 + 364
8 WebCore 0x3215a502 HandleRunSource + 358
9 CoreFoundation 0x30e9dacc __CFRUNLOOP_IS_CALLING_OUT_TO_A_SOURCE0_PERFORM_FUNCTION__ + 8
10 CoreFoundation 0x30e9d32e __CFRunLoopDoSources0 + 358
11 CoreFoundation 0x30e9c03e __CFRunLoopRun + 646
12 CoreFoundation 0x30e1f49e CFRunLoopRunSpecific + 294
13 CoreFoundation 0x30e1f366 CFRunLoopRunInMode + 98
14 WebCore 0x321ae0f0 _ZL12RunWebThreadPv + 396
15 libsystem_c.dylib 0x377bf72e _pthread_start + 314
16 libsystem_c.dylib 0x377bf5e8 thread_start + 0
知道可能导致此问题或如何解决问题的方法吗？