Are you saying you cannot update the Bios ?
You Flash the Bios before you boot your system either by using the BIOS 'Flash' utility or from DOS after a floppy boot and running the flash program. So Norton should not be running.
Gigabyte usually have a search & flash utility that runns from windows.... it searches the Gigobyte web for the latest bios's and you get to choose which one to dowload and flash.
You have to make sure that Flash is enabled in the bios before attempting to do this.