Corsa-B.uk - Vauxhall, Opel and Holden Corsa B Owners Club

got an issue with my head unit!!.... the unit has power, i can take the cd in and out of it, but it wont give its full power.... now if you turn the ignition on, and then turn the key slighty more just before the car starts up it works finem(the unit turns on and works fine), if you start the car up normally the unit doesnt turn on but does have power going through like before!!! bugging me.....

it use to work fine ive had the car in the garage sitting there for a few months, ive tried a brand new unit, does the same thing !!!