Mute button malfunction on Pavilion 15. Mutes and unmutes itself - the F6 button light works and the speakers follow the light, either off or on, mainly off, and the only way I can get sound is to use the loudspeaker icon bottom right and adjust the volume. That releases the speakers for a while, but is becoming a less reliable fix. I reinstalled audio driver, bios and firmware. Tried to do the same with chipset, after HP automatically identified my machine and offered drivers for it (I just followed what people had done on the forums), but I got the message during a failed chipset reinstallation that my machine did not fill the minimum requirements for the update (!). By the way, I don't understand much of all this. I am pension age and not a techie. I also have a fault on the HP assistant (unhandled exception, XML - this document does not have a root) and very curiously, since i did all those reinstallations today, I can no longer type a capital X with the shift key on the left hand side. I mention these because I do not know if there is a connection. HELP please!!