Remove all Power from the Computer, open it up, ALWAYS touch a metal part of the Computer to Ground youself against Static Electricity, remove all Cables from the MotherBoard, take note, later you will need to replace them, then remove the Battery, it looks similar to a coin? Leave it alone, just have a coffee and relax a bit for at least 10 minutes. Replace the Battery and all the cables to the MotherBoard, Start it up and tap appropiate key to get into BIOS, usually "F1" or "delete", find your Time and Date settings, they just went back to Default, as when the Computer was built, adjust them to Current time, then "Save and Exit BIOS".
Reboot should fix it, if not Post back. What I think it is, is that something has adjusted your BIOS, we just adjusted it differently?
Edited by Drovers Dog, 17 April 2010 - 06:24 AM.