Just came across this behavior which I could reproduce like this:
1. Go into a zipfile
2. Do a file comparison of the file in the zip with another file not in a zip
3. Here it ends............
Can no longer reproduce it like this

While trying to reproduce it again I got TC to look like this by just going into a zip file.
Here is the screenshot.
The second row of tabs is hidden but you can see the color of the active tab. When I move into a different folder. The rows show fine again.
Running XP Home SP2 NL, TC7b4