This one is strictly for electrical engineers . The 40 odd Dell Vostro A840 laptop we have on campus sometimes stop booting with this warning screen. If you figure this out, do drop me a line.
The AC power adapter wattage and type cannot be determined.
The battery may not charge.
The system will adjust the performance to match the power available.
Please connect a Dell 65W AC adapter or greater for best system performance. To resolve this issue, try to reseat the power adapter.