Have you tried downloading the update again? You may have a bad BIO file. Did you try using iFlash from a DOS boot disk? If you are doing a recovery from a USB key, make sure no other BIO file is in the root directory except the one you want to flash.
I've tried IFlash via diskette after which I get a failed flash update message. I've tried the recovery BIOS method several times (for last BIOS version and some prior versions): they all fail with the following message: '<NUMBER> bytes overflow'....