Update to 18.0.1 disconnects Firefox in Windows XP ( perpetualy "Connecting" on tabs)
After updating from 17.0.1 to 18.0.1 Firefox will not make any external connections in Windows XP (SP3 running all updates as of the date of this post. )
Preceeding the failure during the installation of 18.0.1 the update process the installation message box states "Checking compatibility of add-ons" and apparently hangs. After the firefox process is killed. Firefox is restarted and will not connect to any website, although internal cached links work - initial firefox start page and setup page "about:config"
Reverting to the previous 17.0.1 resolves the issue.