Network connection broken through everything EXCEPT chrome

My system apparently interprets network connections as broken, except when going through Chrome, which can reach the internet just fine. Safari, Firefox and system update all see a broken internet connection. Running network diagnostics says that ethernet, network settings, and ISP are fine, but Internet and Server are failed.

I am running OS X 10.6.8 on a 2011 macbook pro. I've tried connecting through both ethernet and wifi with identical results.

I originally ran across the problem when trying to run a java application that I use often, only to find it being reported as broken. I tried to do a software update and found that the update tool though that I wasn't connected to the internet.

Subsequent searches on the text "software update can't check for updates because of a network problem" showed many instances in which software update reported no network connection, but browsers could connect just fine. Some of these turned out to be apple's servers being down, some were other problems.

Fixes suggested included:
-deleting and recreating connections in network preferences.
-creating new user to test if default settings work

I tried both with no success.

Any ideas as to what is causing this?

Sounds like you have a proxy or something similar (download manager maybe?) installed on all your browsers except Chrome.

solved

So I determined that my DNS was the problem. I figured this out when I tried to ping a known ip address, which was successful, but attempting to ping an alphanumeric address failed. I believed the reason that chrome continued to work is because it builds some kind of DNS cache locally ("DNS prefetching")

In particular, I had edited the mDNSResponder a while back to disable Bonjour advertisements (per this article: Mac OS X v10.6: Disabling mDNSResponder will disable DNS). Everything was working fine until I restarted for the first time a week later.