Does this ever happen to you?
Someone with a vaguely familiar screen name IM's you, "Is that you, _name_?". You reply, "Yes it is! Who is this?" . You wonder if it's an old friend or a past co-worker, you recognize the name, but can't associate anyone to it. You wait. ... and wait ... but never get a response.
Ugh. Not a good feeling. Good thing life goes on :)