Hello I am one of the experts here on Just Answer.com
can you please go to this link http://support.apple.com/kb/ht1353 and tell me the exact model of ipod you have
One thing that could be happenning is that the Ipod is on repeat for a single song depending on your version of Ipod you will notice
On the song screen, a half inch below the word iPod in the upper left corner, you will see two arrows in a loop pattern.-If it's white, it will only play a album once then stop.-If it's blue, it will repeat the whole album until you stop it.-if it's blue with a 1 on it, it will repeat the same song till you stop it.
Again the location of repeat depends on your ipod so if you can tell me the exact version I can tell you exactly where to look
Please let me know if the repeat feature is turned on
To tun it off you will simply need to press it a couple times so it turns white