Pardon my brevity... And please note that I'm using the bug forum, even though I'm using the beta.
When I press Alt+A to open the Favorite menu, the menu opens, but the A key is still passed, meaning that the tree view or the file list (whichever has focus) can take that A key press and select the next object that begins with A.
The Alt+A key combination should eat the A!
Edit: Corrected typo.