Question: I am trying to migrate an old VS2005 application to VS2010. I am trying to debug that application, but after I cleaned the project then tried to build it, MSVSMON.exe failed to start and an error message appears.

Any ideas? Googling around I find that I am trying to debug a 32bit app in a 64bit debbuger?
Cleaning the project does not fix that problem?

Answer: 
> 
> In Regedit, navigate to
> HKEY\_LOCAL\_MACHINE\SYSTEM\CurrentControlSet\Control\Lsa
> 
> 
> Right-click Lsa and create a new DWORD
> 
> 
> value Name it DisableLoopbackCheck Set its value to 1
> 
> 
> Reboot (instead, I killed the msvsmon.exe process and restarted Visual Studio)
> 
> 
> 

Check also the comment of soandos I use that also!

So many years and windows still uses regedit!
Windows 7 x64, VS 2012, VB.NET

I fixed it like this:-

1. Create a shortcut on your desktop to "C:\Program Files (x86)\Microsoft Visual Studio 11.0\Common7\IDE\Remote Debugger\x64\msvsmon.exe".
2. Right-click shortcut and select "Properties" from the dropdown menu. Select the "Compatibity" tab, tick "Run this program as administrator" and click OK
3. Create a shortcut on your desktop to "C:\Program Files (x86)\Microsoft Visual Studio 11.0\Common7\IDE\devenv.exe".
4. Right-click shortcut and select "Properties" from the dropdown menu. Select the "Compatibity" tab, tick "Run this program as administrator" and click OK.

To start VS2012:-

1. Double-click the msvsmon shortcut icon (that you created above, to launch msvsmon). Wait for the "Visual Studio Remote Debugging Monitor (Administrator)" window to display before continuing ...
2. Double-click the "Visual Studio 2012 Professional" shortcut icon (that you created above, to launch VS2012)
3. In VS2012, ensure standard toolbar is visible.
4. In VS2012, ensure "Solution Platforms" dropdown (on standard toolbar) is visible and set to "x86".

and debug now works (for me anyway) ...

However after 15 minutes or so, debug may stop working and you may get the msvsmon error again. If that happens, simply close VS2012 and msvsmon and then start again (from "To start VS2012:-" above) ...