The deal is, of course, that someone has to invite you to share such-and-so folder. Fine. My correspondent in Australia has done so, BUT...the invitation -- by the time it got to me -- had been somehow aliased: instead of receiving an invitation to share from Bill Gibbs, I received one from Mark Jones.
As you probably suspect, I spoke to Bill about it, and he DID send an invitation, but is as puzzled as I about the weird name. We both think that I'm sharing (something) with Jones, but who cares, right?
This is wild. Also incompetent, but, what the hell, it's MS, true?
Sounds like a problem with your correspondent’s Live ID login. He may have used a different name when creating the account (an alias) and then forgot about it.
Be sure to check the email address that the invite came from.
I sent an invitation from my hotmail account to my work account just now and everything worked as expected.