The bad guys have discovered a nifty exploit for WinAmp. You can get the fixed 5.13 version from http://www.winamp.com/player/
From McAfee's writeup of the vulnerability:
This detection covers a 0-day exploit targeting WinAmp 5.12 that allows remote code execution via a specially crafted play list (.pls) file. Such exploit files could be executed with little user intervention (such as visiting a website that hosted malicious files), and the end result could be the silent installation of any number of viruses, trojans, and potentially unwanted programs.