Problem:

Some Editor tabs and windows (Media Management, Libraries, CD/SACD,....)cannot be found.

Solution: 

All those tabs can be managed from Pyramix settings.

See also that you can change the behavior when closing those tabs : Dock back or Hide/Close floating Tabs when closing them.

Go in All settings > Application > Desktop Layout and look at the Tab Windows section.
By clicking in the Status column for each tab window, you toggle between present / not present status.