Just a reminder that WPAD is a special blocked keyword after recent DNS Server security updates. This prevents sites with an unconfigured WPAD entry from allowing devolution beyond their own level. The symptom you see most often might be that when...

The Feb 22, 2010 update for ISA Server 2006 is the current high-watermark hotfix level: http://support.microsoft.com/default.aspx?scid=kb;EN-US;980067