Some of these LS gurus might have something else to say about this but I've never had nor heard of such a problem. I can't imagine why LS would cause those problems unless perhaps there's a module loading that's somehow screwing with stuff. LS itself only loads modules, it doesn't really do much else on it's own. I use Trillian so I don't know how MSN, AIM or Yahoo behave.

Reset Explorer as your shell and see if you continue to have problems.