Firefox can’t find any websites.
I have no problems when using IE or Opera for the same websites.
I’m using IE to post this since FF can’t find the avast forum… 
Hi Bob, looks like to me you need to reinstall the product
I’ve already done that with no change…
Hello bob3160,
You have been a victim of chrome spoofing I guess. So go here with IE:
https://bugzilla.mozilla.org/attachment.cgi?id=267411
Then copy the text you find there as firefox.js and place it in your profile folder.
Try these tests within IE: http://www.mozilla.org/quality/networking/testing/datatests.html
polonus
Check you haven’t blocked Firefox in your firewall. Disable your firewall and enable Windows firewall temporarily and see if you can connect. (Disconnect from the Internet before switching over, so you don’t leave yourself open to attack while changing from the one to the other.) If you can connect, you’ll know it’s a firewall problem. Try disabling Webshield temporarily and see if that has any effect.