Removing old version of MSN Messenger from Windows XP Pro

I recently upgrade to MSN Messenger 6.2.  I am having difficulty deleting the previous version of MSN Messenger 4.2??

I can be signed out of MSN 6.2 and no other MSN messenger is running that I am aware of and then someone will sign in and my old version of MSN 4.2 starts up.

Can someone please try and help me remove the old version of MSN.  I tried add/remove programs and searching for MSN old files.

Thanks!

Tom - frustrated in Toronto