Why get Platform property of VCConfiguration object hangs sporadically for Visual Studio 2010?

I have a VCProject and try to get the Platform from one of its Configurations.

I found the Visual Studio hangs at VCConfiguration.Platform, the rate is about 50% (5 out of 10 runs). The code isn't executed in the main thread. If there any specify care should I take to get property form a VCConfiguration instance? The version of Visual Studio is 2010 Professional SP1.

Thanks for your help.

VCProject vcpj = (VCProject)info.project.Object;
IVCCollection cfgs = (IVCCollection)vcpj.Configurations;
foreach (VCConfiguration vcc in cfgs)
{
   string configName = vcc.ConfigurationName;

   if (configName == "Debug")
   {
      VCPlatform vcPlatform = vcc.Platform;
      ...

The call stack from Visual Studio is:

     [sleep、wait、or join]    
     mscorlib.dll!System.Threading.Monitor.Enter(object obj, ref bool lockTaken) + 0x14 byte   
     Microsoft.VisualStudio.Project.Framework.Implementation.dll!Microsoft.VisualStudio.Project.Framework.Implementation.MSBuildProjectCollectionXmlServiceImpl.AcquireGlobalLock(bool writeAccess, Microsoft.Build.Construction.ProjectRootElement elementToChange) + 0x5e byte   
     Microsoft.VisualStudio.Project.Framework.Implementation.dll!Microsoft.VisualStudio.Project.Framework.Implementation.MSBuildProjectXmlContainerImpl.GlobalCheckout(bool writeAccess) + 0x19 byte   
     Microsoft.VisualStudio.Project.Framework.Implementation.dll!Microsoft.VisualStudio.Project.Framework.Implementation.MSBuildProjectServiceImpl.CheckoutProjectXmlWrapper(bool writeAccess) + 0x24 byte   
     Microsoft.VisualStudio.Project.Framework.Implementation.dll!Microsoft.VisualStudio.Project.Framework.Implementation.MSBuildProjectServiceImpl.GlobalCheckout(bool writeAccess) + 0x67 byte   
     Microsoft.VisualStudio.Project.Framework.Implementation.dll!Microsoft.VisualStudio.Project.Framework.Implementation.ConfiguredProjectImpl.ConfiguredProjectImpl(Microsoft.VisualStudio.Project.Framework.Implementation.UnconfiguredProjectImpl unconfiguredProject, System.ComponentModel.Composition.Primitives.ComposablePartCatalog completeCatalog, System.ComponentModel.Composition.Hosting.CompositionContainer parentContainer, Microsoft.VisualStudio.Project.Framework.INTERNAL.VS2010ONLY.ProjectConfiguration projectConfig, Microsoft.Build.Evaluation.Project project) + 0x217 byte   
     Microsoft.VisualStudio.Project.Framework.Implementation.dll!Microsoft.VisualStudio.Project.Framework.Implementation.UnconfiguredProjectImpl.LoadConfiguredProject(string name, System.Collections.Generic.IDictionary<string,string> configurationProperties) + 0x1e5 byte   
     Microsoft.VisualStudio.Project.VisualC.VCProjectEngine.dll!Microsoft.VisualStudio.Project.VisualC.VCProjectEngine.VCConfigurationShim.InitializeWithEvaluation() + 0x97 byte   
     Microsoft.VisualStudio.Project.VisualC.VCProjectEngine.dll!Microsoft.VisualStudio.Project.VisualC.VCProjectEngine.VCConfigurationShim.PlatformShim.get() + 0x2d byte   
     Microsoft.VisualStudio.Project.VisualC.VCProjectEngine.dll!Microsoft.VisualStudio.Project.VisualC.VCProjectEngine.VCConfigurationShim.Platform.get() + 0x5 byte