C# – Global.asax parse error after minor change and revert to previous version

The project in context is:

• ASP .NET Web Application
• .NET Framework: 4
• Platform Target: x86
• IDE: Visual Studio 2010 Ultimate SP1
• Multiple projects in solution with ASP .NET being the startup project.

It has been in production for months without glitches until yesterday. I cleaned up the [Global.asax] file (removed unused using statements, refactored, etc.), ran the solution and got the following error:

Description: An error occurred during the parsing of a resource required to service this request. Please review the following specific parse error details and modify your source file appropriately.
Parser Error Message: Could not load type 'CloudTech.ATS.WebClient.Global'.
Source File: /global.asax Line: 1
Source Error: Line 1: <%@ Application CodeBehind="Global.asax.cs" Inherits="CloudTech.ATS.WebClient.Global" Language="C#" %>

Here is the Global.asax Markup:

<%@ Application CodeBehind="Global.asax.cs" Inherits="CloudTech.ATS.WebClient.Global" Language="C#" %>

Here is the Global.asax.cs Code (with internal code removed):

using System;
using System.Linq;

namespace CloudTech.ATS.WebClient
{
    public class Global: System.Web.HttpApplication
    {
    }
}

After wrestling with this error for a while, I searched, restarted my computer, performed a full clean on the solution, force rebuilt but with no avail. Frustrated, I finally changed only the web application target to "Any CPU" and it worked. Unfortunately, "Any CPU" is not an option or a solution to the issue at hand. Changing it back to "x86" brings the same error back. This happened once and since then, no combination of target platform or debug/release configuration works anymore (same error).

Furthermore:

• My development machines are all x64.
• Checked in the solution, had multiple colleagues test on their machines (both x86 and x64) with the same result.
• Restored the entire project to a clean state from 3 days ago and the error still persists!
• Verified tat absolutely NO changes were made to the Web.config files, or any other files in the solution for that matter.

Lastly, the only change to my development systems has been windows updates (regular security updates) and I have tried the solution on systems without updates with the same results.

Any help would be appreciated.