Well.. It just occured to me right now. I haven't crashed while opening a new PM, however when opening already made one it does. -- It does it completely at random.
False. Not completely random. The last person who IMed me posted this:
http://img185.echo.cx/my.php?image=hackerthedae6gd.jpg
I could open the PM in history to see it, it's just opening it that causes the crash. Perhaps the phrasing of image?
EDIT: I had someone send me it, and when he did, I crashed answering his PM.