Fixing Windows Live Messenger's Sign-in Issues

Possibly this is old news for everyone else, but until recently a lot of MSN users from where I work (including me) were reporting sign-in issues on Microsoft's Windows Live Messenger client. No definitive solution was ever found: I and a couple others switched to Pidgin – which works as long as it's configured to connect over HTTP – but most have simply stuck to older Messenger versions which are known to mostly work.

Today, while looking for references about Windows Mobile's Messenger client, I stumbled upon this article on a registry-based fix for the issue. I don't use Microsoft's client anymore, so I haven't tried it; but it's worth a shot if you'd rather not switch softwares. See also this comment about an alternative, if more radical, solution.