I've been trying to load a project from a SourceGear Vault Client that has a plug-in for Visual Studio 2010. After selecting the solution file, the solution explorer populates with the associated projects but appends (unavailable) to the end of each project name.
The usual remedy is to reload each unavailable project but in doing so briefly reveals all files within each project but then VS quickly hides them and makes the project unavailable again.
So far, I have tried opening the code in VS2015, removing all related source control information from the .csproj and .sln files, and deleting the associated .suo file. Nothing has worked yet and I have exhausted all the known fixes.
Thanks for your help.
For clarity, I'm copying @PeterRitchie solution that worked for me, below.
You could try running Visual Studio in safe mode to see if a 3rd party plugin is to blame: devenv.exe /SafeMode – Peter Ritchie