I've run into an issue with my MPS4 & syncing:
I have a GC and MPS4, using the iPad NuVo app as well as the color NuVo touch pad. I use iTunes and a mac mini server with Lion osx and latest version of itunes software.
I switched syncing to a different mac computer (OSX Lion as well) but now the mps4 mac sync program hangs when it gets to track 1501 and won't sync the rest of the tracks (there are about 8,000 tracks in my iTunes folder, or about 90 gig). At first I thought it was an issue with the mp3 file but I tried deleting the file but it still hangs on a different song at track 1501. Then I tried going back to the original iTunes computer & same thing, it hangs at track 1501.
When I first set it up it synced with all 8,000 tracks & worked really well with the exception of not transferring all of my album artwork.
I've tried restarting the mps4 using the network, but that doesn't seem to fix it