Well, I have a spindle of Ritek DVD-R 2X disks that I bought recently very cheap, because I think they are no longer in production. They burn at 2X on my 107, but only at 1X on a 106, both drives with the latest firmware at the time of the test. So I think it is a problem of the disk and the firmware. Those disks you tried may be old, and replaced with new versions, so the firmware may not recognize them properly. I suggest you try another brand before returning it.