Xperia X8 :: Won't Charge Unless I Switch It Off

My experia X8 won't charge (USB or the same cord on the mains charger adapter) or from a car charger unless I switch it off and then plug in the charging lead with the phone still off. Once I've done that the red/green indicators come up ok.I can then switch it on and it continues to charge. I can move the cable and the light will go off, Sometimes I can jiggle it and it will come on sometimes not. If I unplug the cable it normally won't start to charge unless