truncated songs in itunes

I tried to download ipod music back into itunes after hard drive crashed. nearly all songs will play for about 10 seconds and then go on to the next song. if i use the scrollbar i can scroll ahead of the stop spot and the song will play to the end. i used liberator software and they said that i should just delete all the songs on the ibook and download from the ipod again which i did to a different directory but the songs are still corrupted--that is they stop and then skip to next song. i backed up all of the songs onto CDs and then reimported them into itunes on a different mac but the same problem occurs? I have the latest version of itunes.?/ help!?