Tunebite converts songs for me fine, when i play them on my computer they are perfect. However, when i sync the songs onto my ipod, they get all screwed up. For example, a 4 minute song will be a 4 minute song on my computer, but a 15 minute song on my ipod! Whats going on here???
thanks 
it could be the codec it uses to convert the music.
Check the settings and choose something simple like 192Kbs CBR MP3 and see if they work.
If they do then start encoding with VBR, different bitrates and work your way back to your preferred settings. Either you will find what is stuffing your ipod of it will all misteriously work again 
Don’t be surprised if you get option 2.