Civil 3D Toolspace missing tabs
If you are working in Civil 3D 2011, and you look up and you are missing the Prospector and Settings tabs in your Toolspace, then you are not alone. I've been experiencing this problem for months now. It wasn't until AU class CM316-2U (AutoCAD® CUI: Tricks and Traps), that I found out what is causing the problem. How did this come up in a CUI class? This was an unconference class where the discussion was driven by the participants, and the problem was mentioned by Barbara Piper, who had figured out that it is the PREVIEW command that causes this behavior to occur.
Here is the normal Toolspace, and then the incomplete one after running the PREVIEW command.
You can restore them by clicking in the correct icon (twice) in the Palettes Panel of the Home tab of the Ribbon. Notice that the buttons are all depressed (indicated by the blue background) showing that the Prospector and Settings tabs are visible, even though they are not. That is why you have to click it twice.
In my tests, you only have to do this once per session of Civil 3D, since subsequent executions of the PREVIEW command do not affect the toolspace.