Recently I had this weird error where Microsoft Visual Studio 2010 (VS 2010) debugger was not getting attached to Microsoft Internet Explorer (IE). The only change was that IE was upgraded from IE 9 to IE 10. Till before the upgrade everything was working fine. The error is pasted below.
Attaching the Script debugger to process '[XXXX] iexplore.exe' on machine 'XX-XX-XXX' failed. A debugger is already attached.
The solution for the above problem is pretty simple as well. Open the command prompt (cmd) in “Run as Admin” mode. Run the following command.
regsvr32.exe "%ProgramFiles(x86)%\Common Files\Microsoft Shared\VS7Debug\msdbg2.dll”
“regsvr32” is a command line utility provided my Microsoft to register and unregister dlls in the Windows Registry.