Strange MP3 noise

[fa299238]

I've searched trough some posts, didn't find anything, but I just can't imagine I'm the only one who has this problem. It seems that, when downloading somewhat recent mp3's, there is a possibility that Winamp (and probably some other players too) act strange.
Symptoms:

• stuttering/hammering sound
• playback indicator moves from !right to left! and back (sometimes)
• bitrate smoothly increases or decreases

When does it happen? Sometimes in normal playback, sometimes whilest skipping.

Example? Dido - White Flag (the most popular version on P2P networks)

Note: I don't want to advertise for P2P software, I just want to explain the problem

Is this a codec problem, or are this bad versions put online accidentely/incidentally? I don't think I downloaded a "bad" version, since I have some experience with mp3's. (I rip them myself, as this is completely legal. And I never have problems with mine. Why am I downloading anyway )

This problem occurs on different pc's with different OS'es, and with different songs. On one computer, a song causes trouble, and on the other, it doesn't.

Does this sound familiar to anyone?