Ctrl + Dot (ShowSmartTag) not working in Visual Studio 2012

It's CodeRush that caused the issue and I uninstalled it, then SmartTag works again. My guess is that CodeRush replaced VS2012's built-in SmartTag entirely.

In my case it was Web Essentials that caused this issue. I disabled it, and now all works well.

All keyboard shortcuts can be viewed from Tools > Options > Environment > Keyboard. What does your View.ShowSmartTag command say about current shortcuts?

If you try to assign CTRL + . to anything, it will tell you if the shortcut is used by something else...