don't know anything more at this time, but it seems like the whole amp shuts down, including the footpedal, and as I said this happens when on standby mode for a long time. I'm wondering if line6 company manufacturers built in a safety mode for the amp not to overheat if on standby for too long. I checked the fuse and it was ok. If I wait a few minutes after shut off, it will come back on again. any ideas? thanks!