Cmos is where BIOS settings are stored. I have seen BIOS's are now so streamlined, you have very little control of how your system runs. Mostly,imho, this is contributed to the XP OS, and how IBM clones live and die by M$ rules and apps.
BIOS, Basic Input Output System, use to allow for so many control settings, and if your having a hardware problem, you need to know if the hardware is PNP. If not, turn PNP off in BIOS and start the computer, then install the software for the hardware.
Flashing the CMOS is a way to wipe all your BIOS settings by a power or ground jumper, but you should try restoring BIOS defaults first. Then when the system starts up, it will find your hardware and the OS will install the drivers. You then need to check if it is M$ drivers or your hardware drivers. Reinstalling AGP or Audio hardware drivers on top of the programs already installed folders are usually acceptable.