I'm getting seriously hacked off with Messenger at the moment. I've been trying to add a contact for the last couple of days only to be greeted with either the "the service isn't available at the moment" or "this contact doesn't use Windows Live" errors. I've tried reinstalling and the registry trick, but to no avail.

But bizarrely, they are showing when I log in via www.live.com. Yet they are talking to me through Messenger. The window even appears and I click to add to my contact list, but it just takes me back to the Live page saying that I'm already connected with them.

Any solutions?

Hmm...  do they appear in your contact list on the Web Messenger?  Can you talk to them through there?  If so, it might be a problem with syncing your contacts to Messenger.  If not, try removing them from the website, then re-adding them through Messenger.

Yes, as I said they are appearing in the messenger on live.com and I can talk to them. But I don't want to use a browser version of messenger just to talk to some select people!