Give us a few clues...
What OS are you using?
What computer are you using?
What version of iTunes are you using?
Does it do it on all tracks - just MP3 tracks, just iTMS tracks?
Are you playing through external/internal speakers or wirelessly?
If wirelessly, what level of security does your router run?
Is the pause mid-song, at the start of a song?
What's the crossfade set to in iTunes preferences?