Hello, I'm playing on a Marshall DSL40CR on the OD2 channel with the channel LED indicator red and footswitch plugged in. Once in a while the amp will simultaneously drop the volume to zero, the LED channel indicator on OD2 turns green, and the volume and footswitch are unresponsive. It's happened twice now, and it will fix itself if I completely shut down the amp and restart it. Does anyone have any idea what this could be? Thank you!