can write CDs okay but not DVDs

[johnsees]

My mother-in-law was using her Sony DVD writer (not sure of the model, sorry) and Roxio to make copies of a DVD. She got the first one made fine, but the second one failed with some error about a buffer being full. (She's old ; that's the best error message I've got.) She tried again after restarting the computer, with same result. I had her use DVDShrink to make an ISO (I thought it would be easier to use than Decrypter) and then try to burn it with Imgburn. She says it failed to write sectors 243104-243135 after taking a "tracking servo failure." I thought maybe her drive had died, so I had her create a CD by filling it up with music tracks. She says it made the CD, and it plays just fine.
Does anyone have any suggestions about what's causing her problem?
Thanks.

[Richard_G]

A DVD writer has two lasers, one for DVD burning and the other for CD burning. It is very common if either the laser dies for a drive to still work with the other type of disc.

[johnsees]

Well that's very interesting! Thanks for the info.

[Nilfennasion]

Do you have a drive you can take to her computer and put in? That would be the best way to determine whether the drive happens to be the problem. Yank her drive out temporarily and put a spare in its place (I still have an old drive I am not doing anything with). Then repeat the attempts to burn DVDs (using a DVD+RW or something else that can be rewritten after a failure, preferably). If the attempts to burn are successful on the spare drive, then that makes the problem very likely with the drive. Is the drive under warranty?

[johnsees]

Yeah, swapping out the drive is always my first preference; it's just kind of a PITA because of having to take one of mine out, drive to her house, and then install it, you know...
And no, hers is too old for warranty.
Thanks.

[johnsees]

Yeah, swapping out the drive did the trick.
I also found out, by playing with the old drive before I took it out, that the write speed on a DVD+RW constantly varied from 1x to 4x, and she told me that it had been doing that for a while. I don't really know what's in a DVD writer, but it made me think of that "servo failure" error message she took.
Thanks again, folks.