Problem with folder icons

I designated my Music folder to use as the sharing folder for FrostWire. (http://www.frostwire.com/)
When I did that it changed the icon for the file from the Windows Vista default Music folder icon (The glossy green-ish one), to the ordinary folder file icon.

I tried reversing this change by alocating a different file (The downloads folder) as the sharing folder, that folder also changed and the Music folder didn’t change back.

I then tried changing the icon back using the folder properties, but vista wouldn’t let me. (The only option was to change the thumnail displayed inside the folder on the icon.)

So then I tried creating new folders, moving my music and downloads into them, deleting the previous folders and renaming the new folders to Music and Downloads. Then I entered the folder properties and this time there was an option to change the folder icon, but I couldn’t find where on the hard drive the glossy green-ish folder icons were stored.

Can anyone tell me where those icons are? Or provide any other method through which I can correct this madness? I know it’s not a big deal, but I like to have my folders organised.