Yesterday I had to analyse a properties-file so I used T-Windows for resourcebundles. After exporting "unknown" segments to an rtf-file, I had the Concordance missing.
There is no Concordance function in the Tools window - I take it this occurred after you closed the Analysis dialogue?
What happens if you highlight the Workbench window (and hit F3)?
The Workbench window keeps turning "grey" as if another window would have been opened, but it doesn't appear.
If this happens straight after opening the TM, could it be that you have set the Project/Filter settings window to appear by default, but it's either hidden behind other windows, or may have been moved outside the visible screen area? If that is the case, Workbench should become operational if you just hit Return, and the problem should occur again when pressing CTRL-P. Can you confirm that?