I ran into similar situation with my dvd burner also, although I am using Mandrake 10.0 and Sony DRU-530A. Here is the short version of how I get my burner to burn DVDs:
In K3b, there is a setting to set the burn speed for the DVD. By default it is probably set to "Auto". I got my burner to work by setting to "Ignore".
Long version:
When I read mine message, my error message has more than just ":-( Failed to change write speed: 8310->16620", it mentions something about incorrect option parameters.
So I created an ISO image, using "Create Image Only" option in K3b first. Then I tried to "Burn DVD Image" using K3b. And that didn't work either, so I copy the command, open the command prompt (Konsole), and type in the command without the options. So, it was something like:
Code:
/usr/bin/growisofs -Z /dev/sr0=TempDVD.iso
And it worked on my DVD burner.
So, after some trial-&-error using the "Simulate" option in K3b, I find out that it was the "-speed=xx" option that caused the problem, even if I set the speed to 1x or 2x. And that's how I find out setting to "Ignore" would remove that "-speed=xx" option.
I hope that help. Took me a while to figure out too. Maybe because I am new at this.... (Just migrate from Windows XP a month or so ago).
The option to simulate burning really help out a lot.