DVD-R's fail to read on my Mac after a while...

[angopop]

Hello. I am finding that DVD-R's (that is DVD minus Rs) that I have written are rejected by my computer, the same computer that has written them, sometimes immediately, sometimes it will read the DVD but weeks or months later will just get rejected -- meaning I insert the drive, the disc does not get read by the computer and is ejected. I use TDK, Memorex and Sony DVD-Rs and find the problem with a small percentage of discs. I've tried cleaning my drive with a laser cleaner which helped at first but not lately.

I've got a 1.6 GHz PowerPC G5 running 10.4.6.

I had Apple replace the drive a few years ago, which at first also solved the problem, but the problem returned. Sometimes the discs can be read fine by another computer, so it is puzzling.

I found a forum online where it was suggested that you need to use certain manufacturing numbers on a variety of brands to find ones that will work, which sounds very complicated.

One possible solution is buying an external drive, but I'm not sure if this help.

Questions for people are:
1. Has anyone had this problem and how have they remedied it?
2. What kind/brand of blank DVD-Rs do you recommend and why.
3. How do you clean your Mac's superdrive?

Thanks.