Has anyone encountered: "Could not load file or assembly 'aspnet_compiler... Failed to grant permission to execute"?

I am encountering a strange build issue in .NET 3.5. The compiler is crashing when it attempts to build a Web Deployment Project.

C:\Program Files\MSBuild\Microsoft\WebDeployment\v9.0\Microsoft.WebDeployment.targets(531,9): error MSB6006: "aspnet_compiler.exe" exited with code -532459699.

Which leads to:

Could not load file or assembly 'aspnet_compiler, Version=2.0.0.0, Culture=neutral, PublicKeyToken=b03f5f7f11d50a3a' or one of its dependencies. Failed to grant permission to execute. (Exception from HRESULT: 0x80131418)

That section of Microsoft.WebDeployment.targets is this:

<AspNetCompiler 
      PhysicalPath="$(_AspNetCompilerSourceWebPath)"
      TargetPath="$(TempBuildDir)"
      VirtualPath="$(_AspNetCompilerVirtualPath)"
      Force="$(_Force)"
      Debug="$(DebugSymbols)"
      Updateable="$(EnableUpdateable)" 
      KeyFile="$(_FullKeyFile)" 
      KeyContainer="$(_AspNetCompilerKeyContainer)"
      DelaySign="$(DelaySign)" 
      AllowPartiallyTrustedCallers="$(AllowPartiallyTrustedCallers)" 
      FixedNames="$(_AspNetCompilerFixedNames)" 
      Clean="$(Clean)"
      MetabasePath="$(_AspNetCompilerMetabasePath)"
/>

If I try:

aspnet_compiler.exe -errorstack -v /MyProject -p C:\MyProject -f -c -d .\TempBuildDir\

I get:

Unhandled Exception: System.IO.FileLoadException: Could not load file or assembly 'aspnet_compiler, Version=2.0.0.0, Culture=neutral, PublicKeyToken=b03f5f7f11d50a3a' or one of its dependencies. Failed to grant permission to execute. (Exception from HRESULT: 0x80131418)

File name: 'aspnet_compiler, Version=2.0.0.0, Culture=neutral, PublicKeyToken=b03f5f7f11d50a3a' ---> System.Security.XmlSyntaxException: Invalid syntax.

I could build fine until I made a small code change. I've reverted the change, but I continue to encounter this error. Other team members can build the exact same source.

Things I've Tried

Reinstalling VS
Reinstalling Web Deployment Projects addin
Restarting
Building with nant
Building in VS
Building from the command line with aspnet_compiler.exe

Has anyone encountered this type of error before? My next step is to reformat, unless I can find something else to try.

Solution

I was finally able to build after running a full build in nant with:

nant build

I thought I tried this before. Anyway, it works now--no thanks to the error message. I imagine that my nant config for MyProject is missing a dependency, or something.