Clean Dapper Install inserts bad proxy line into apt.conf, breaks all forms of apt, dogs and cats living together, mass hysteria

I was able to replicate this on two boxes within my home environment.

When doing a clean, straightforward-from-the-CD install, I get an intial error on getting security updates, but the install continues. I get a fully up-and-running Dapper install. The networking for browsing is just fine, I can use the included firefox etc, but none of the repositories will connect.

After changing repositories, and even blacklisting ip6, I still couldn't get the package manager (I tried both the add/remove interface, the synaptic interface, and the command line apt-get interface, all of them failed).

I found a clue here: http://www.ubuntuforums.org/showthread.php?t=257988&page=2

As it turns out for some reason the installation inserts a single line into the file at:

/etc/apt/apt.conf

the line is:

Acquire::http::Proxy "false";

Once I removed that line, everything worked fine.

I did a fresh install on a second box, had the same problem, removed *only* that line and everything worked again.

I'm on an internal network, 192.x.x.x, I don't know if there's something to my environment that caused it to want to do that.