Question : Proxy blocking sites on IE7 (intermittantly) but not IE6...

My domain controllers are running IE6, and our proxy is running a Blue Coat SG800 Series, with SGOS version 3.2.6.1.

Most of our clients are using IE6 as well.  Internet access and proxy blocking work great.  Only a few have IE7, but the problem is that about 50-70% of those on IE7 block ALL websites with the proxy denied screen.  

If I bypass the proxy, it usually works.  HOWEVER, we have had times where bypassing the proxy has caused "page cannot be displayed" errors.  Also, we've experianced it working fine on the local admin account (still on the domain), but domain user or domain admin accounts almost never work correctly.

What could be causing this?  We've looked through the Group Policies as well as the proxy rules and haven't found anything alarming.. Any tips are appreciated.

Answer : Proxy blocking sites on IE7 (intermittantly) but not IE6...

Solution: Added proxy local policy rule allowing IE7..