im not sure, but you could try this
go to the application data in the windows folder (or if xp/2000, documents and settings then application data) the go to microsoft, msn messenger,
then you will need to find your user account number
a easy way of doing this is with a program i created from wtbw code..
Download this program here
once you have found your number, enter the folder with that number
goto user tiles, then open each .dat file in paint, and make your corrections, click save
and see what happens
as long as you dont change the filename you should be fine