If your MP3s were encoded using a different ripper/encoder than iTunes, there may be embedded icon data stored inside the MP3 file. This can cause iPod to read beyond the actual end of the music data, where it will read a portion of another song. Read AppleCare Knowledge Base document #61638 for more information and suggested solutions.
I'm a passionate, long-time lover of Apple products, and was a civil draftsman and graphic designer before creating the iLounge web site. My prior projects include work for The Los Angeles Times' LATimes.com, and the company Creative Domain, where I developed websites for clients including Columbia Pictures, Disney, Fox Studios, Universal Pictures and Warner Brothers. As the Publisher of iLounge, I direct the site's community forums, photo galleries, iPod User Group, and general business affairs, which have grown under my watch to over sixteen million page views every month. I'm happily married with one daughter, one dog (Rocket the Wonderdog), one cat (Ferris), many iPods, iPhones, iPads, and two turntables.