The four star reviews aren't four star reviews.

The number of stars is a rough indication of how easily you are likely to be able to get the file. One star is something like a modem user with no available upload slots, while four star is a broadband user with free upload slots. Stars provide no guarantee of playback quality.

Unfortunately, many people do a really bad job of ripping music - and others quite happily propogate the bad tracks once they've downloaded them.

So there is a fairly high chance that the tracks are corrupt. Your previous good quality may be done to luck. (The fault you describe sounds typical of a poorly ripped track).

If tracks you have downloade previously still play fine, then you can be confident that the problem lies with the new tracks you've downloaded.

If there is a problem with previously okay tracks then you need to take a careful look at what has changed on your system.

Try downloading winamp from www.winamp.com - this has excellent playback quality with little system overhead - so should help you decide whether it is your system of the tracks which are at fault.

Mark