eMac spitting out a burnt DVD


Mac Enthusiast
I just burnt some stuff for a friend onto a DVD-R disc. I used the disc many times on my own computer, but after leaving it at his place he put it in and after 45 seconds of churning it spits it back out. The disc is a reputable brand and is in perfect condition as I used it. Any ideas?

His eMac has a DVD-RW and is running 10.4.1.