Unable to debug Visual Studio 2010 addin or suddenly stopped working

I have created a new addin for Visual Studio 2010 using standard addin template. The sample works fine, then I start making some changes and adding more dependencies. Yes got some compilation errors and have fixed them. Now after starting debugging a runtime error is thrown, so fixed that.

Now If I start debugging, the addin no longer gets loaded and also won't show in Addin Manager (VS2010 -> Tools -> Add-in Manager). Now this is really getting me upset.

Used our friend google to find a solution but no luck. So started looking at places where addins were loaded from, aha.. I found the issue.

1. Looking at "C:\Users\Saif\Documents\Visual Studio 2010\Addins" I have found the addin file was renamed from "MyAddin2 - For Testing.AddIn" to "MyAddin2 - For Testing.AddIn_" ie.. an "_" in the end. I think this might have done by visual studio, ie.. since visual studio is unable to load the addin it has renamed by adding "_"

So renaming back from "MyAddin2 - For Testing.AddIn_" to "MyAddin2 - For Testing.AddIn" started loading the addin.

2. Also verify Project Properties -> Debug

1. "Start external program" : "C:\Program Files (x86)\Microsoft Visual Studio 10.0\Common7\IDE\devenv.exe"
2. "Command line arguments" : "/resetaddin MyAddin2.Connect"
3. "Working directory" : "C:\Program Files (x86)\Microsoft Visual Studio 10.0\Common7\IDE\"

The inside of a computer is as dumb as hell but it goes like mad! ~Richard Feynman