When I have my Firefox browser opened I can't unhide the taskbar. If I minimize Firefox the taskbar will unhide normally. It gives the appearance that Firefox is too large and the cursor cannot connect with the taskbar. I keep the task bar at the bottom of the screen but the same thing happens if I move it to the right or left edge and maximize Firefox. If I put the cursor on the top edge of the task bar I can activate the 2 ended arrow that is normally used to move edges of app windows. In this case though it does nothing as far as pulling the top edge up a bit. I think if I could make the taskbar just a smidgen taller I could unhide it with Firefox open. Windows live mail does not interfere with the taskbar.