.mp3 icons changed to a new image and won't change back

[Calvaria]

Here's what happened. I had a music file (that I recorded from youtube) open in Audacity, I then converted it to .mp3 (did this many times before). The new mp3 file had the same icon as my other mp3 files. I then double-clicked it and instead of playing in Winamp a window poped up asking me what program I would like to use to play this file! I cancelled and double-clicked again but the popup appeared again. I then clicked on "Keep using Winamp". At that moment the mp3 file changed its icon to a blue note against a white background (Winamp doesn't have such icon). I checked file associations both in Winamp and in Windows (and changed it back and forth): it doesn't respond to changes within Winamp but does respond to changes from within Windows but when I reassociate mp3 with Winamp it changes it back to this blue note icon.
At the same time Winamp stopped responding to Shell Options menu settings, always displaying Play, Enqueue and Add to Bookmarks items when right-clicking on mp3 files (but works fine when right-clicking on folders).
Any ideas what happened and how to deal with it?