Webb .. I upgraded mine by putting update.zip and gapps.zip on the root of my sdcard then booting with those 2 keys held down. Truthfully, they weren't the only 2 files on my sdcard, I had a backup of all my apps on there too, though the update files were the only 2 in the root directory of the card.
Perhaps you should try updating from your SDcard instead if you are hafing flash drive problems ????