A couple of weeks back, I downloaded an MP3 file of "The Most Beautiful Song" by the German band Lunik. Although it played fine in Winamp, when I loaded it in dBpowerAMP, with its XAudio decoder, it burped on it, reporting its length to be 2 days and 6 hours as opposed to 3 minutes and 34 seconds. I could explain why this happened, and a draft of this post did, but I ended up writing 4 paragraphs of general waffle.
Instead, I'll tell you that I used Foobar2000, a barebones media player for Windows which includes the ability to fix MP3s that report the wrong length. Add a file to the playlist, right-click on it and choose 'Fix MP3 Header'. The file should now accurately report its length.
