I've associated my Notation product with MIDI (.mid) files - why does some other media player play those files in my browser?
A couple of media players use a bit of a "stealth" approach to running their software in your browser. Here are two that we are familiar with, and the specific steps that (should) work for not having them immediately playback MIDI files.
QuickTime (full installation - the Player-only version seems to behave a bit better and allows the "regular" Windows associations to rule its behavior):
1. Open QuickTime
2. Select "Edit/Preferences/QuickTime Preferences" then the "Streaming" tab
3. There is an option called "Instant On." Checking this option will automatically play all audio media in QuickTime when a web page is opened or a linked filename is clicked. Uncheck this option.
1. Open RealPlayer
2. Select Tools/Preferences
3. In the left hand panel, under General, select Playback settings.
4. In the bottom of the right-hand panel, make sure that "Instantly play media links instead of downloading them" is unchecked.