HELP! My G5 won't read burned DVDs anymore!

[bbernardini]

I'm fairly certain this is due to the 10.4.7 update, but somebody on the Apple board thinks otherwise. I have a 1.8 dual G5 with some extra RAM and the original DVD drive. It will read all factory pressed CDs and DVDs, as well as burned CDs. It will also burn DVDs and CDs with no problems. (I've made a few and tested them on standalone players.) However, it refuses to mount ANY burned DVDs, either those I've burned myself, or those burned by others. I put the disc in the drive, which holds it for 5-10 seconds, then ejects it again. I know the media is good (Taiyo Yuden manufactured in Japan). Needless to say, I'm at a total loss. Thoughts?