A MP3 that the player can't handle would do that. Re-encode it at a bitrate you know your player can do.
Worth noting: Some MP3s on the internet and P2P are purposely corrupt.
today i was adding some mp3's to my mp3 player and when i started playing the songs on it, the song timer was counting second by 2 like 2-4-6-8-10 and so on, but the music was playing at normal speed. the timer would go up to about 4-5 mins and then stop and skip over to the next song. whats worng?