Toshiba Satellite A25-S2792 w/ XP & P4 has greenpower chord is lit and yellow battery light is flashing when power chord is plugged in. After I press the power button, the power chord light changes to yellow, begins flashing and the battery light goes out. Removing the battery gives the same results. Pressing and holding power button down for 20 seconds w/ battery out yields same result as well. Suggestions?