I had the same thing happen..it would go off at all hours, beep beep beep..no error code, then would go on as if someone had put something in to cook. The beeping was driving me crazy..why? what the heck was going on with this stupid thing? It got to the point where I just would unplug it and plug in only to use it. One night I left it plugged in and it went off about 3 am so I went out and looked at the screen and it appeared to have a smiley face on where the numbers were..some were lit some not and I swear it looked like an evil smiley face...Well I chucked that thing in the nearest dump...have no idea what it was up to but obviously no good lol.
watch for the smiley..when that happens..get rid of it lol! it may be a clone Mooooooohahahaaa :/