I have an Acer Aspire 6920 laptop with media controls to the left of the keyboard, but I can't get them to function. For a while the lights under the buttons worked, but could not make the comp do anything. Now the whole of the volume control is lit up blue as well as the mute button, and none of the buttons respond at all. (My computer isn't actually on mute, its just as if these particular controls turned themselves off. Any suggestions?