I currently have a Samsung 14" QX411-W02UB. It was running Ubuntu 12.04 64bit flawlessly until I installed the Intel Graphics Installer and it ended it making my touch-pad no longer work. I decided to just do a fresh install to resolve my issue. The installation kept failing (ubuntu would produce a blank screen after rebooting.) So I checked the media for defects and this is what message came up.
Integrity test failed:
The ./pool.main/l/linux-signed-its-quantal/kernel-signed-image-3.5.0.-23-generic-di_3.5.0-23.3.5~precise1_amd64.udeb file failed the MD5 checksum verification.
This is my file:ubuntu-12.04.2-desktop-amd64.iso
I used both unetbootin and the Linux universal installer to transfer the file to the USB drive.
I've attached a picture of the message.
I've checked and I can install the 32bit version of Ubuntu without an issue.
I've also tried the alternate 64bit version as well.