The Dell BIOS is access by hitting the F2 key (?) when you first start out, and it will let you into a special section of the computer that keeps the setting when the computer is turned off.
Normally I would just say to get professional help. Maybe a local geek to look at it.
Its probably a Windows update or a driver issue that causing the problem.
Anyone else want to take a stab at this?
LOLOL, I agree. :)