[ubuntu] Can't install alternate CD from USB

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http://ubuntuforums.org – Hi im trying to install ubuntu 12.04 with full hard disk encryption. After downloading and installing the Ubuntu live CD, I learned that truecrypt doesnt support full disk encryption on linux. I also learned that the best way to get "nearly full disk encryption" on ubuntu is by installing it from the alternate install CD. I tried that, but something is wrong with my CD reader/burner so it doesnt boot up when i insert the cd. My thought here was to take the .iso that I downloaded on my unencrypted Ubuntu system, use Unetbootin to make the usb drive. The usb drive used for this is ex (Hardware)