Here's what gdisk gives me.
GPT fdisk (gdisk) version 0.8.1

Type device filename, or press <Enter> to exit: /dev/sda
Caution! After loading partitions, the CRC doesn't check out!
Warning! One or more CRCs don't match. You should repair the disk!

Partition table scan:
MBR: MBR only
BSD: not present
APM: not present
GPT: damaged

Found valid MBR and corrupt GPT. Which do you want to use? (Using the
GPT MAY permit recovery of GPT data.)
1 - MBR
2 - GPT
3 - Create blank GPT

Your answer:
How do I set the data as read-only? And does that require ubuntu to be installed, or is that still when it's running from the CD?