[ubuntu] Can't open items on the launcher

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http://ubuntuforums.org – I'm new to Ubuntu and Linux so I apologize in advance if this is a stupid question. I installed ubuntu 12.10 on my 8GB USB drive, which I formatted as FAT32, using Universal USB Installer from pendrivelinux.com, and gave it 4GB of persistence. I booted it up, experimented with a few things, installed ubuntu restricted extras, and everything seemed to be working fine. But then I tried to open the dvd I had in my dvd-rom drive, and it simply won't open. I click the icon on the launcher and nothing happens. I'm getting the same result when I click on casper-rw, system, and os. I tried eject (Hardware)