Hey I'm glad I can access you directly today, Jason.
I've been on comcast since Sep '12 and I have had persistent problems with DNS resolution, but only on linux machines. Get this - even setting my linux machines to use 184.108.40.206 for DNS does NOT resolve the problem.
I had a laptop running linux and couldn't even bring up bankofamerica.com;
if I started Windows in a virtual machine, windows was able to resolve DNS without issue;
as long as Windows was running in the virual machine, the host computer (linux) was able to resolve;
if Windows went to screen saver, DNS would stop resolving.
The virtual guest uses the host's networking hardware and software, so why would receiving a request from Windows get a result while linux gets a stalled-out non-response? I ended up having to plug linux machines into routers that would then talk to the modem, AND THAT WORKS.
There's some kind of stupidity at play in your network, but I'll be moving outside of Comcast's service area this year, so I don't even care if it gets fixed.