There may be a way within your system to Configure a DVD drive, if this issue is not related to inconsistent manufacture quality of DVD media. In the past (search) this issue code came up along with a few others, in some instances there may have been firmware or hardware failure; an occasional dusty laser lens, or a bad batch or brands of disc media. And the quality/speed issues could still be in the running.
Some info may be found by searching that code in google, include OS X; but watch what happens when you add or remove the 10.5 part of the search text. It may make even less sense.
I have iDVD software in my Leopard 10.5.8 systems, but usually use an older version of Burn, a free-ware application, to backup some digital images on DVD or CD media.
•Error code 0x8002006E when burning a disc
http://geekfromthewest.blogspot.com/2011/11/error-code-0x8002006e-when-burning-d isc.html
Maybe someone will reply w/ recent experience in resolving this (or researching it?)
Good luck & happy computing! 🙂
PS: some indication from other online users implied
the error code suggested a hardware related issue.
Also see above link, added.