I have been having MM remain in memory (in my process list). Usually 2 or 3 versions, crashed I assume. I figured reinstalling it would fix the problem, so I ended all processes of MM, and ran into the MMHelper problem when trying to do this.
I ran ProcessExplorer and found that my error was Winamp running under Explorer.
Why? Well, I believe that this MMHelper.dll is what is used to communicate, you see, I had configured Winamp to be my default player (with a external sound card). It was buggy, so, its no surprise this had remained in memory for days.