When you say "ping works on affected machine" were you pinging a local IP or something internet based like your ISP?

also, Do other browsers work on the machine? and have you tried opening diffrent webpages?

A possible cause is security software (firewall) that blocks or restricts Firefox or the plugin-container process without informing you, possibly after detecting changes (update) to the Firefox program.

Remove all rules for Firefox from the permissions list in the firewall and let your firewall ask again for permission to get full unrestricted access to internet for Firefox and the plugin-container process and the updater process.

See:

• https://support.mozilla.com/kb/Server+not+found
• https://support.mozilla.com/kb/Firewalls

Hi, ping works on any internet IP. Tried alternate pages, same problem. All other machines on local network do not have this problem. They have normal access to internet. Both firefox and ie8 do not work on this machine. I've tried to repair the connection through windows and IE, but same problem. From the IE diagnostic log a message 12007 crops up that says limited or no connectivity. I'm beginning to suspect SP3 overwrote an ethernet driver. It's an old card. But when I tried to system restore, the message was no changes had been detected. That was curious since my workgroup name had reverted back to the XP default. I fixed that problem so my lan file and printer sharing all work ok.

If a ping works then that means that the connection is OK.
So there seem to be other (routing) problems with the network setup.
Did you check the connection setting and the setting in your security software (firewall)?

Does it work if you boot the computer in Safe mode (F8 on the boot screen), with network support if necessary?

I checked the connection settings and the internet connection displays connected and under the status shows traffic flow. Two firewalls, windows and norton are disabled temporarily. Also, the browsers do not connect in safe mode. I'm really scratching my head.

I also checked the driver for the ethernet card and it is up to date and the device is listed as working properly in device manager. Does the browser have to look at the registry somewhere to find the connection?

just a note to say I finally found the solution, came from MS KB949377...reset registry with provided script worked fine, but took hours, whew.