Since installing the Service Pack 1 for Visual Studio 2010, my .sln files for Visual Studio 2005 have not been opening.
This turns out to be, because I had VS2005 set to need Admin Privileges to run, to allow some remote debugging. But I also needed to set this for the Visual Studio Launcher, as this is what chooses which Visual Studio to open the solution file. In applying the service pack, it appears the need Admin Privileges setting was lost.
To test this, I found the VS2005 executable and remove the Admin Privileges requirement, and then my 2005 solutions opened.
But I couldn’t find where the Launcher was, so searching registry for .sln I found the file uses:
VisualStudio.Launcher.sln
looking for this you find it at:
HKEY_CLASSES_ROOT\VisualStudio.Launcher.sln\Shell\Open\Command\
which for my machine points to:
C:\Program Files (x86)\Common Files\Microsoft Shared\MSEnv\VSLauncher.exe\
Now knowing the Launchers name/location I can set needs Admin Privileges and everything works as it was.