Shoutbox

It may be due to the fact that you have too many backgrounds and when MSN Messenger tries to load these to show you the previews, it crashes.

Go to

C:\Documents and Settings\<user>\Application Data\Microsoft\MSN Messenger\<msn id>\Backgrounds

<user> is your windows user name

<msn id> can be found using this tool

If you right click on some of the files and open with a picture viewer application, you can see what the background is. Try deleting some of them and see if it still crashes MSN.