youtube videos volume bar doesn't work w/ firefox sometimes

hey guys, i'm having this minor but annoying problem with Firefox. every now any then when I move my mouse over the volume button while I'm watching a Youtube video in order to get the volume bar to pop up, nothing happens. if i click repeatedly on the button and go crazy it will pop up, but it will not let me slide the volume bar up and down. i don't remember having this problem with Safari. it's sort of like the browser isn't recognizing my mouse cursor hovering over the volume area in order for it to trigger the bar to pop up, if that makes any sense.



thanks!

 

bump.