iPod Touch sync problems

I have had problems for quite sometime with my ipod touch. It would connect okay, but when I tried to copy music or videos to my ipod from my computer, I might get a couple of songs copied, then the ipod would disconnect and my USB wireless stick would fail. The computer would then display an "internal error" caused the ipod to fail.

I thought the issue was my ipod, so today I bought a new iPod touch (5th generation), and, lo and behold, same problem. The first time it failed during an update to the new iOS, and now I have been trying to copy an album to by ipod and it has failed about 12 times just trying to copy music.

- I tried moving USB cords to new locations on the PC.

- I performed a diagnosis on iTunes and according to it my ipod connection is fine.

- I have updated iTunes to the latest version.

- The iPod software is current.

Any ideas? I'm out of patience and out of ideas.