A friend recently ditched her Windows PC and bought a new Apple PowerBook. Of course, she wanted to use her iPod with it, so I helped her get set up.
First, rather than network the two computers together, I just used PodWorks to get her songs onto the new PowerBook. No problem there: it's a great program and did exactly what it was supposed to do: 5,000 songs were now in her iTunes library.
Then came the problem: when trying to sync the iPod with the Mac, we kept getting "error type -36" and it would stop copying her songs to the iPod. We'd restart the sync, and after a while it would stop again.
To try to fix this, I restored the iPod software. Although this didn't solve our type -36 problem, it did fix other minor issues (such as the iPod's icon): if you ever switch over to a new computer, it's a good idea to restore your iPod and start fresh.
After some other tests, I discovered the problem: the iPod cable. We were using the cable that she was using with her Windows PC, which was a USB 2.0 cable. I'm not sure why we kept getting the error type -36 problems, but once I used my FireWire cable to sync her iPod instead, it worked fine: The entire library was copied to her iPod without a hitch -- and faster than when we used the USB cable, I might add.
I don't know if this is a common issue, or if it was just because of the initial size of the sync (5,000 songs or so). But it seems that if you're having problems syncing your iPod with a USB cable, try using a FireWire cable instead.