IPCop 1.4.21 and Copplus can ping outside but cannot browse.

Greetings Experts,
       I have been using IPCop and DansGaurdian as a proxy / filter at our school for the past 5 years.  Last week the HD crashed on that box so I figured it was time to build a new box.  I have 2 Dell Dimensions so I used one of them to install IPCop 1.4.21 and CopPlus 2.2 ( I belive ).. running DansGuardian 1.4.1 anyway.  
       All in all, everything appears to be working just fine on the new IP Cop, with 1 MAJOR problem, I can ping outside, FTP outside, TELNET outside, but cannot browse past the Green Interface.   Squid is running on both Red and Green interfaces ( these are all I'm using ), Proxy is up and Transparent on Green.   Content filter is running.   Can ping google, but cannot browse to it using IE.
       I've read and read and appears is either DNS or more likely a proxy issue.   NO logs in the proxy and sites never even get as far as the content filter.  After many unsuccessful "tweeks", I was convinced I needed a complete reinstall.   After doing that, same results.
        Today I tried a new approach... found another Dell Dimension 2400 PC and installed everything on it using same methods as before.   Same results, all services appear to be running fine, can ping outside, can telnet outside, etc... just no browsing outside from behind the IPCop.    Any ideas on what I could be missing ?