Cannot boot from CD ROM - GA-P35-DS3L

ok, so I put this machine together 9 months ago and my RAM (CORSAIR DOMINATOR 4GB (2 x 2GB) 240-Pin DDR2 SDRAM DDR2 1066 (PC2 8500) x 2 sets) is starting to fail on my GA-P35-DS3L (not sure what revision...). I was asked to run the memtest86 program and provide the results to CORSAIR prior to them issuing a RMA for these. I've run this before w/o any issues but not can't get my MB to boot from CD. I can set the boot order in the BIOS to boot from CD only and it still won't boot from the memtest CD w/ the .iso file. I've tried invoking the boot order menu, manually selecting CD and still it won't work. I get a message that says something to the affect, BOOT FROM CD:, like it's waiting for me to enter Y or N or something...funny thing, my keyboard won't work to allow me to enter anything at this point, but works fine in the BIOS editing. I sware when I ran this before i had to do something to allow my keyboard to register key strokes at this time, but can't for the life of me remember what it is. My keyboard is enabled, as a USB keyboard, in my bios, so I'm all out of answers. Any info would be appreciated!

fairly certain...I followed the instructions. Download the zip file. unzip. burn contents to cd.