Hello all,
Running Thunderbird 17.0 and using CCleaner portable v3.26.1888. Now, with the "clean Thunderbird sessions" ticked, it actually reverses the Quick Filter Bar option under View> Toobars> Quick Filter Bar. When I say it reverses the option, I am referring to the fact that CCleaner changes the bahavior of the show and hide options. When operating properly, a tick against this option should show the toolbar and when unticked, it should hide the toolbar. After cleaning the Thunderbird sessions (with CCleaner), a tick hides the toolbar and an untick shows the toolbar (eg, reversed logic).
Apparently, this has been a problem for some time now as many Thunderbird users have reported the problem in the Thunderbird forums and the fix has always been to untick "clean Thunderbird sessions" to fix the problem. This worked for me on my windows 7 Home Premium laptop and my XP Desktop as well.
Here is a link to a Thunderbird forum post where the problem is discussed: http://forums.mozillazine.org/viewtopic.php?f=39&t=2481041
FYI