Just re-read my post above and realised that I called my solution a 'fix'. That's incorrect, it's merely a workaround as the original problem with the system freezing after configuration changes using the Gnome Networking tool persists on the machine. However, manually editing 'interfaces' has enabled me to regain connectivity.
-- Ralink Wireless USB/PCMCIA/PCI hangs PC https://launchpad.net/bugs/34902 -- ubuntu-bugs mailing list ubuntu-bugs@lists.ubuntu.com https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs
