Windows 7: Firefox 12 Jumplist problem

the Firefox 12 start menu and taskbar jumplist are missing. it was ok in my previous Firefox 7 version. the rest of jumplist eg. IE, Notepad, mOffice are working ok.
if i right click on a Firefox icon on taskbar, i can see the jumplist. but if it is a pinned Firefox icon, there is no jumplist.

i have always ticked both the privacy options under taskbar and start menu



using
Firefox 12
Windows 7 Ultimate 32 bit

pls help, thanks.



uninstall and install of FF solved the problem.