Every time I go to use programs on my computer while on a Firefox session, when I return to Firefox, the menu that appears when I'd typically press the Alt key drops down. Every time. The only way I can get it to stop is by exiting out of the session entirely and reopening it. There is no option on my Firefox settings that can help me disable the action.

I have not installed or changed anything in my settings, it began happening suddenly, and has become an interruption in my workflow. Any ideas on what might have caused or what I can do to fix it?