Hello to everybody and yes, I am aware that this is an old Thread...

Anyway, I decided to post it right here, since this is totally related to this very subject, and this subject related stuff is a little bit rare to find over Net...
Well, the "vanishing" problemo with the Windows 7 Taskbar right mouse click on:
a) IE9:
- Start InPrivate Browsing
- Open new tab
b) Mozilla Firefox 12
- Enter Private Browsing
- Open new tab
- Open new window
is like the
@Brink says - some privacy cleaning software like "CCleaner" and/or,
I says "Privacy Eraser Pro" can do this very easily...
So, how can we repair it?
One customer of mine has this problem just yesterday, and I successfully resolve it.
Well, first I create a System Restore point, before and tamperings of mine as a caution measures all here...
Then I try first to clean all the garbage in Web browsers (IE, MF) and reopened them (since the upper mentioned both privacy software also deletes the very well known "index.dat" file in IE browser...) , so I thought that this also might produce upper mentioned problemo all here...
Nope, that was not the problem, so I further try to recreate IE9 and MF12 Shortcut icons via Win 7 Taskbar (pin it again in to the Taskbar and delete the old ones). And that do some help for MF, but, IE9 was still big problemo...
Then I go via Accessories - Disk Cleanup, and clean everything...
Finally, I try to go via "Taskbar and Start Menu Properties, and play (engage/disengage) with the Privacy options all here ("Store and Display recently opened programs in the Start Menu" and "Store and display recently opened items in the Start menu and the taskbar")
Finally, the last one just mentioned above do some real help all here in a second, and now my customer have again the Private browsing mode, both in IE and MF Shortcut icons right mouse clicks on it....
Anyway, I hope that this will help to all others with the same problemo!
Cheers to all!