disabling autoplay on C:\...

Hi,

I've a friend who unzipped an installation file to his C:\, and then began
installation from there. But the thing is, when he's done and start deleting
the unzipped files, he discovered the system will autoplay C:\ when he
enters it, and when he right click c:\, there's an "AutoPlay" option.

Any idea how to disable it? He's annoyed that Windows attempts looking for
the deleted autorun file, and telling him it can't be found.

Thanks