|In addition to the above I would wonder why this message appeared even if the setting is enabled in the BIOS. I would think that someone had to remove a cover from the case. If it wasn't you, then you may want to figure out who it was.|
Also, removing the battery resets ALL the BIOS settings to defaults. You need to enter the BIOS and reset the date & time, boot order, and possibly other values, like integrated hardware, etc.