Squidguard not blocking websites

[agent69]

Hello,

I'm having issues blocking websites using squidguard. If the preferred DNS server is set to the local Windows DNS server squidguard will not block any site, but if I set the preferred DNS server to the pfSense IP address squidguard will start blocking the websites.

External domains will resolve just fine if the IP address of the pfSense box is set – for example, "ping msn.com" returns 4 quick results.

If I try to ping one of my internal machines using the IP address of the pfSense box, it doesn't resolve -- For example, "ping Dell" (where Dell is the name of one of my Windows desktops) resolves as "dell.test.local can't find dell: Non-existent domain".

Any help would be much appreciated.

Thanks,
Sam