Ursprünglicher Beitrag von: Paul L Daniels ,
The problem is quite common. It's the fault of one of the main NEC/TOKIN capacitors located directly beneath the CPU (on the other side of the board). The reason why it works on battery but not AC is because there's no significant ripple in the power when running from battery, but on AC there is a fair amount which causes unreliable behaviour. Replacing the capacitor is not a trivial task even for those who deal with surface mount replacements. Typically we just break off the old TOKIN capacitor and install a set of tantalum caps in its place.