I'm running Windows Live Messenger (Build 8.1.0178.00) without MP! running & my operating system Windows 2003 Enterprise Edition Enterprise 5.2 R2.
What happens is when someone changes his/her display picture or sends a custom emoticon while I have a window active, my WLM will freeze while it downloads the custom material and then resume when it's downloaded (ex: The display picture will flicker and change after the freeze, the custom emoticon will show after the freeze).
The windows install is brand new so I don't think the problem is there.
I don't know what's wrong but I'm writing this to tell you that I have the same problem, although the freezes also occur when someone is sending a file or just sending large messages (like more than 5 rows of texts). It's crazy!