In my ubuntu 14.04 machine, and only for one of the user accounts in that machine, firefox has begun to show all those right-click context menus, pop-up lists of suggestions, and the list of recent sites (the one offered by the 'down arrow' just at the left of the 'refresh' button in the address bar. The result is that all them are useless because everything is black and i can't see anything. As i told, this happens only in one user account. The other users see Firefox as usual.
package 'firefox' ver: 40.0.3+build1-0ubuntu0.14.04.1
Someone figures what can be happening? Thx in advance