The only other possible explanation is that the laser of your drive is dying. RW and normal writable discs require different power levels in order to burn. I cannot remember which one requires a higher power level to burn, RW or normal writable discs. Assuming writable discs require a higher power level to burn, it is possible that the laser in your drive has weakened because the drive is getting old. The laser may be too weak to write to writable discs but can still manage RW discs. Eventually, it may get to the point where it won't write to normal writable discs either.
There isn't any solution for this except to send the drive back for repairs. Not an option unless your drive is still covered by warranty.
Sorry, but a "focus or tracking error" message typically means something hardware related has gone wrong. I don't think it is something you can fix by messing around with drivers or cables.