After installing an extension, I sometimes get the following error

A problem occurred when loading the Microsoft Visual Studio menu. To fix this problem, run 'devenv.exe /resetsettings' from the command prompt. Note: this command resets your environment settings.

Open up Developer Command Prompt and try the following:

devenv /setup

and then start Visual Studio. If you still get an error, try starting it from the Administrator Command Prompt with the command

devenv

Reference: Stackoverflow