Comment 11 for bug 1117292

Same issue: 13.04 64-bit, ubuntu server.

The errors pgoetz reported were actually probably false postives (I see the same thing): http://askubuntu.com/questions/180218/why-does-integrity-check-fail-for-the-12-04-1-alternate-iso

...which makes me wonder what he did that actually solved it. pgoetz - did you do anything else differently? Did you choose the same boot line from the grub menu?

The preseed (default set of auto-answers to the installer's questions, which is in the grub boot options of the kernel boot line) is /cdrom/preeed/ubuntu-server.seed for the "Install Ubuntu Server" choice I've been trying.