Very new to Ubuntu & not linux savvy. I have the same 'unable to find a live medium...' issue as noted here "http://ubuntuforums.org/showthread.php?t=2185752" here.
I was trying to install on a 2 year old Dell Inspiron 1545. Background - got a new machine, the Dell was slow and Windows would frequently give me a smart drive warning. I figured it was time to wipe off Windows and go with Ubuntu as a web browser. Currently, I'm checking the disk and doing a system restore for Windows first on that old machine (it's taking a few hours).
Meantime, I want to check the DVD I burned(using the other, new machine-Windows 8, blech). However, I'm so new to this I'm lost even with MD5SUM. I was unable to check the burned DVD from the command prompt. I'd type cd D:\ and the screen would show "d:\" and then take me back to the command prompt.
So, um, HELP!