My Windows 8 machine will turn down the volume to about 20% for no reason at all. All my controls are maxed, loudness equalization is checked under playback devices options, i've told it to 'do nothing' on the communications tab and it still keeps lowering the volume. I don't think there is an after-market card in this machine; it's not mine, I use it at school, so I don't know all its specs. Most annoyingly, this has happened before and it went away on its own and I don't know why. Any other theories?