SA 7 in Win 8.1 running SSMS as different user

Seems like I have a problem with getting SQL Assistant 7 (or 6.5) registered correcly with SSMS when logging in as another user by using right click > Run as different user in Win 8.1. The context menu in the menu bar is not showing (it worked in Win 7) and nothing happens when writing sql statements. I am however able to see the SQL Assistant menu when right clicking a database in object explorer. If I log in in a normal way as the logged in Windows user (with or without Run as admin) everything works as it should.

SQL Assistant was installed by using Run as administrator. I also start SSMS by using Run as administrator. The usual procedure (Options, MS Management Studio, Advanced and yes/no on Register SQL Assistant Addon) has been performed as well. Have tried installing SA using my other account (using Run as different user), it didn´t work either.

Any ideas?

The symptoms indicate that the main add-on for SSMS doesn't get registered. Since you don't get any errors when you do Unregistered/Register, I assume that Windows allows the application make necessary changes in the system registry (in redirected virtual locations), but then silently erases them.

I suggest trying to lower Windows UAC level or disable it temporarely so that the application changes are allowed to stick (please see http://techzend.com/disable-user-account-control-windows-81/ for details) and after registeeribng the addon, restore previous UAC settings.