i asum ur using windows xp
wmp 9 is made by microsoft and so is windows so wmp 9 is set to take it over this how to stop it
Right click on your cd/dvd rom drive in my computer click on properties and then click on the autoplay tab and bring the dropdown box to music files click on select action for platform.
In that box should be win amp select it it and hit ok
i hope that sorts it!