I've tried several tips from this thread, to no avail.
I have downloaded the liveCD installer, x86 & x86_64, checksums are fine. In tools that allow downloading the iso I have downloaded it with the tool as well as trying my downloaded copy.
I have used the Universal USB Installer, UNetBootIn, and a tool called Win32DiskImager to write the image to a USB drive. None reported any errors. Each tool and each version of the installer has the same problems:
When booting, I have the option in BIOS to launch
The former comes back with a "Please insert bootable media. Press any key to continue" error. The latter boots into a bootloader, which gives me these options:
Any option selected causes the screen to blank out and the USB drive's LED to blink the same way it does when ejected, then about ten seconds later the computer powers down.
Try Ubuntu without installing
Test disk for errors