After first putting the disc in the drive, run Nero InfoTool and let it look at the disc. For some reason even if windows couldn't identify the disc, Nero will and until you remove the disc (or reboot), it'll run fine.
Another thing that can help during playback problems is DVDIdle: http://www.dvd-idle.com/dvd-idle.htm
It makes your drive read ahead and cache the data.
Hope that helps