The master / slave settings are per controller (drives on the same controller are on the same ribbon cable).
On each controller one drive should be master and one should be slave. If there is only one drive it should be master (or sometimes the jumper settings allow for a single drive setting).
Assuming that the SATA drive is on a controller on its own, AFAIK there should be no conflict between this and the old HDD and the DVD.
BTW, I assume that SATA works in pretty much the same way as non-serial ATA regarding the cabling / jumpers. But, in any event, if the SATA is on a discrete controller, that shouldn't be the issue.
Can you switch the DVD and old HDD jumpers around so that DVD is slave and old HDD is master?