That guy was being a frustrated jerk and should have stayed calm and attached detailed logs and been professional.
Don't be that guy.
Apparently this was caused by some thrash in the Ubuntu mirrors and the issue can't be replicated here anymore and the OP is going to shut up now.

Admin - feel free to lock this thread as you see fit..
***End Edit***
I have tried multiple machines on multiple networks.
I have tried 32 bit and 64 bit versions of 12.04 LTS server and desktop with ISOs downloaded yesterday.
Instillation does not.
I don't care what broke it, but something did and I need help reinstalling, please.
I also used a 12.04 LTS CD that I had burned a few months ago with the same results.
Please update when you have an idea what is happening. I tried both the main US mirror and the main Canonical server for repro sources.