fastmp3player.com is a boobytrap. It masks as a normal mp3 from any artist you can search for, but when you click on it, it opens a webpage and starts installing viruses. Delet this file, NOW.

If you get a dialog saying that the file is in use by some other program, please don't believe this: it's a trick the programmer used to get you to keep the darned thing there. Instead, use an unlocker program (this one is good: Unlocker - Reviews and free Unlocker downloads at Download.com, instructions on how to use it here: UNLOCKER 1.8.6 BY CEDRICK 'NITCH' COLLOMB)

Presto, the evil thing is removed.