first thing i'd suspect is power supply... or try a different outlet...
not seen issues like this... so i'm certain that its not common.
maybe you can take your unit to a music store and try using their power supply to test....
please do as above advised: please check if the power supply is the cause
in such case, please get a DC-3g replacement from your Line6 dealer: http://line6.com/support/docs/DOC-4269
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