New Post: error MSB4062: The "TfsTasks.ExecMulti" task could not be loaded from the assembly

I'm getting this error:

C:\Program Files (x86)\MSBuild\Microsoft\VisualStudio\TeamBuild\BuddyBuildExtensions.targets(298,9): error MSB4062: The "TfsTasks.ExecMulti" task could not be loaded from the assembly C:\Program Files (x86)\Microsoft Visual Studio 9.0\Common7\IDE\PrivateAssemblies\BuddyBuild.Tasks.dll. Could not load file or assembly 'file:///C:\Program Files (x86)\Microsoft Visual Studio 9.0\Common7\IDE\PrivateAssemblies\BuddyBuild.Tasks.dll' or one of its dependencies. The system cannot find the file specified. Confirm that the <UsingTask> declaration is correct, and that the assembly and all its dependencies are available.

I've verified the file exists at the location specified

Here is the BuddyBuildExtensions.targets

<UsingTaskTaskName="TfsTasks.UpdateBuddyBuildWorkItem"Condition=" '$(IsBuddyBuildV2)'=='true' "AssemblyFile="$(TeamBuildRefPath)\BuddyBuild.Tasks.dll"/><UsingTaskTaskName="TfsTasks.ExecMulti"Condition=" '$(IsBuddyBuildV2)'=='true' "AssemblyFile="$(TeamBuildRefPath)\BuddyBuild.Tasks.dll"/><PropertyGroupCondition=" '$(IsBuddyBuildV2)'=='true' "><BuddyBuildTaskVersion>1.0.85.0</BuddyBuildTaskVersion></PropertyGroup>

...

Line 298

<ExecMultiCommand="$(TfCommand)"ArgumentsTemplate=" unshelve {0} /recursive /noprompt"WorkingDirectory="$(TfUnshelveWorkingDirectory)"ParametersList="$(ShelvesetList)"Delimiter="|"IgnoreExitCode="true"><OutputPropertyName="UnshelveExitCode"TaskParameter="ExitCode"/></ExecMulti>

Any ideas whats going on?  Really confused since I've verified the file exists at the exact location specified in the error message.