Plugin: .midi file worked, now it doesn't.

Hello,
I'm running Windows XP, I have Dreamweaver 6.1, and my browser is IE. My
problem is that now when I want to play any .midi file, a message appears
saying, "Unable to find the plugin that handles this media type. Dreamweaver
looks in both the "Configuration/Plugins" folder, and the plugins folder for
each of your installed browsers."
But before it would just play fine. It happened all of the sudden- while I was
actually working on the web page. And also when I preview it, it doesn't show
it either.
Any help would be greatly appreciated.

Thank you,
Debbie