If, after following Leon's advice, the BIOS continues to display the CMOS Checksum Error message, it means that you need to replace the CR2032 battery on. When the charge in the battery completely drains out, the CMOS is unable to generate a checksum number. This again leads to a conflict between. - BIOS update: If you had recently updated your BIOS of the computer, the CMOS values could have been reset. Enter the CMOS setup and re-enter all the.