If you were using Firefox 3.6.6 or newer, a new preference was added to the Connection Settings proxy preferences in Tools > Options > Advanced >> Network tab - Connection = Settings = Use system proxy settings
The default setting is for Use system proxy settings
If you select No proxy and restart Firefox your problem should be fixed.
for some reason i don't know Firefox stopped accessing the web, i was able reinstall fire fox for a second time and g0t it working again, after i did a restore from before September 24/11.
I had tried all the firewall solutions, and network solutions they did not work. so to fix this try a restore going back to /Firefox 6.xx then using another browser reinstall fire fox. all off my data was still intact when Firefox started up. pew......