ISOLINUX hangs on boot from CD

[PelPix]

I have installed Ubuntu several times and use it as my primary OS. I decided I wanted to wipe my current install and install it again now that I know what I'm doing.

Problem is, both the livecd and the alternate CD simply display the ISOLINUX version info and then progress no further. Not even a "Loading..."
Drive does not spin up.

This is the same PC I've previously installed Ubuntu on thrice, using the same ISO.
What's going on?

[PelPix]

I tried installing from a thumb drive, but that didn't work either, for an entirely different reason. For some reason, the thumb drive assigned itself sda and bumped all my disk drives one letter down. So, all the configuration files said to boot to sdd, when the disk was sdc in actuality.

Just a boatload of problems out of nowhere!