Could not load file or assembly ... The parameter is incorrect

To know what to clear for sure - add the following registry key:

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Fusion\EnableLog (DWord set to 1).

Then you will see output like below. This tells you where asp.net is attempting to load your DLLs. Clear this directory.

LOG: This bind starts in default load context.
LOG: Using application configuration file: c:\app\AtlasAdvisor\web\web.config
LOG: Using host configuration file: C:\Windows\Microsoft.NET\Framework\v4.0.30319\aspnet.config
LOG: Using machine configuration file from C:\Windows\Microsoft.NET\Framework\v4.0.30319\config\machine.config.
LOG: Policy not being applied to reference at this time (private, custom, partial, or location-based assembly bind).
LOG: Attempting download of new URL **file:///C:/Windows/Microsoft.NET/Framework/v4.0.30319/Temporary ASP.NET Files/root/3c8629f7/dfa387b6/Avanade.ViddlerNet.DLL.**
LOG: Attempting download of new URL **file:///C:/Windows/Microsoft.NET/Framework/v4.0.30319/Temporary ASP.NET Files/root/3c8629f7/dfa387b6/Avanade.ViddlerNet/Avanade.ViddlerNet.DLL**.

Looks like a corrupted assembly being referenced.

Clear both:

1. the \bin folder of your project

2. the temp folder (should be C:\Users\your_username\AppData\Local\Temp\Temporary ASP.NET Files in windows 7)

and see if the error still happens

I had to clear

C:/Windows/Microsoft.NET/Framework/v4.0.30319/Temporary ASP.NET Files

Only then did the issue get resolved.

Depending on if your are running X64 you might need to clean up a couple more spots. Just cleaning up my user directory was not enough.

1. %TEMP%\Temporary ASP.NET Files
2. C:\Windows\Microsoft.NET\Framework\v2.0.50727\Temporary ASP.NET Files
3. C:\Windows\Microsoft.NET\Framework\v4.0.30319\Temporary ASP.NET Files
4. C:\Windows\Microsoft.NET\Framework64\v2.0.50727\Temporary ASP.NET Files
5. C:\Windows\Microsoft.NET\Framework64\v4.0.30319\Temporary ASP.NET Files

This list will grow as if you have other versions of the framework installed.