我已经创建了WP8应用程序，当我导航到第三页然后返回主页应用程序时，只有三个页面终止，没有错误，调试器仍然只在Visual Studio中运行输出窗口显示以下日志： 谁能告诉我发生了什么。
'TaskHost.exe' (CLR C:\windows\system32\coreclr.dll: Silverlight AppDomain): Loaded 'C:\Data\Programs\{AFD7ACFA-47D3-4AFF-A2C7-A3129A7CCF3B}\Install\Newtonsoft.Json.DLL'. Cannot find or open the PDB file.
'TaskHost.exe' (CLR C:\windows\system32\coreclr.dll: Silverlight AppDomain): Loaded 'C:\windows\system32\System.Threading.Tasks.ni.dll'. Skipped loading symbols. Module is optimized and the debugger option 'Just My Code' is enabled.
'TaskHost.exe' (CLR C:\windows\system32\coreclr.dll: Silverlight AppDomain): Loaded 'C:\windows\system32\System.IO.ni.dll'. Skipped loading symbols. Module is optimized and the debugger option 'Just My Code' is enabled.
'TaskHost.exe' (CLR C:\windows\system32\coreclr.dll: Silverlight AppDomain): Loaded 'C:\windows\system32\System.Xml.ReaderWriter.ni.dll'. Skipped loading symbols. Module is optimized and the debugger option 'Just My Code' is enabled.
'TaskHost.exe' (CLR C:\windows\system32\coreclr.dll: Silverlight AppDomain): Loaded 'C:\windows\system32\System.Linq.ni.dll'. Skipped loading symbols. Module is optimized and the debugger option 'Just My Code' is enabled.
'TaskHost.exe' (CLR C:\windows\system32\coreclr.dll: Silverlight AppDomain): Loaded 'C:\windows\system32\System.Collections.ni.dll'. Skipped loading symbols. Module is optimized and the debugger option 'Just My Code' is enabled.
'TaskHost.exe' (CLR C:\windows\system32\coreclr.dll: Silverlight AppDomain): Loaded 'C:\Data\Programs\{AFD7ACFA-47D3-4AFF-A2C7-A3129A7CCF3B}\Install\Posh.Mako.Proxy.DLL'. Symbols loaded.
'TaskHost.exe' (CLR C:\windows\system32\coreclr.dll: Silverlight AppDomain): Loaded 'C:\Data\Programs\{AFD7ACFA-47D3-4AFF-A2C7-A3129A7CCF3B}\Install\System.Net.Http.DLL'. Cannot find or open the PDB file.
'TaskHost.exe' (CLR C:\windows\system32\coreclr.dll: Silverlight AppDomain): Loaded 'C:\Data\Programs\{AFD7ACFA-47D3-4AFF-A2C7-A3129A7CCF3B}\Install\System.Net.Http.Primitives.DLL'. Cannot find or open the PDB file.
'TaskHost.exe' (CLR C:\windows\system32\coreclr.dll: Silverlight AppDomain): Loaded 'C:\windows\system32\System.Threading.ni.dll'. Skipped loading symbols. Module is optimized and the debugger option 'Just My Code' is enabled.
'TaskHost.exe' (CLR C:\windows\system32\coreclr.dll: Silverlight AppDomain): Loaded 'C:\Data\Programs\{AFD7ACFA-47D3-4AFF-A2C7-A3129A7CCF3B}\Install\microsoft.phone.controls.toolkit.DLL'. Cannot find or open the PDB file.
'TaskHost.exe' (CLR C:\windows\system32\coreclr.dll: Silverlight AppDomain): Loaded 'C:\windows\system32\System.Runtime.Extensions.ni.dll'. Skipped loading symbols. Module is optimized and the debugger option 'Just My Code' is enabled.
'TaskHost.exe' (CLR C:\windows\system32\coreclr.dll: Silverlight AppDomain): Loaded 'C:\windows\system32\System.Globalization.ni.dll'. Skipped loading symbols. Module is optimized and the debugger option 'Just My Code' is enabled.
The program '[2444] TaskHost.exe' has exited with code -2147220978 (0x8004020e).