iPod freezes during sync

I've had my iPod touch for a couple of months and it worked fine until iOS was updated. Since then I regularly (every day, pretty much) get errors during sync when it freezes and fails to end.

Sometimes I try leaving it for hours but to no avail, sync doesn't finish and the spinning "sync in progress" symbol continues to spin. After that the device seems to keep hold of the file where it records what songs have been played as it doesn't update the count of what's just been played or allow me to upload new songs. Sometimes when uploading new songs via wi-fi it will upload two or three then wi-fi drops out and I have to start again. When I've just bought a new audio play with 100 tracks, uploading three at a time and then having to restart is very annoying.

The only way to get round this is to shut it down and reboot. When I do this the play count of all songs played between the previous two syncs goes up by one, but the "last played" time stamp doesn't get updated.

Whether I try to sync via wi-fi or cable makes no difference, the same error happens both ways. iOS on the iPod and iTunes on my pc have both updated twice since the failures started. I didn't have any errors whatsoever prior to the iOS upgrade.

Any ideas what's wrong? I've unloaded/loaded iTunes, restored iOS on the iPOD and nothing seems to work - is there a way to regress to the earlier version of iOS which worked reliably?