Could not load file or assembly 'antlr.runtime' or one of its dependencies. The parameter is incorrect. (Exception from HRESULT: 0x80070057 (E_INVALIDARG))
All of a sudden I started to get assembly load errors for antlr. Process monitor showed me a BUFFER OVERFLOW was occuring in the Asp.net temporary folder (C:\Windows\Microsoft.NET\Framework\v2.0.50727\Temporary ASP.NET Files).
So I deleted the Temporary ASP.NET Files folder and got a different error:
The current identity (NT AUTHORITY\NETWORK SERVICE) does not have write access to 'C:\Windows\Microsoft.NET\Framework\v2.0.50727\Temporary ASP.NET Files
I then recreated the Temporary folder and gave NETWORK SERVICE write permission, and now it works.