Frustration with Sony DRX 710UL

This is a newbie type question will have an answer that will seem obvious -- but I'm stumped.

I have a Toshiba Tecra S1 with a built-in DVD burner. It's slow and -R only, so I bought a Sony DRX 710UL, expecting a great increase in speed.

The first DVD I made worked fine on the set top box. I'd used a DVD+R that had been around for a while. It wrote at (I believe) 2x.

Then I popped in an 8x DVD and got a DVD that the set top box could not read, another computer could not read, and the DRX 710UL could not read.

Before I made the first 8X DVD, a message from either the drive or the application I was using said that a region had not been set and that not setting a region would cause problems. So I set the region (US/Canada).

I've burned several additional DVD+Rs (Fuji and Verbatim) with various programs (DVD Shrink and DVD43, Nero, DVD Decrypter, 1Click DVD Copy, and NTI CD & DVD Maker). So far, all I have to show for my efforts is 6 hours of wasted time and a stack of coasters.

The Nero system information and disk test all report no problems. ASPI is installed and running properly. The Tecra is a 1.1(or thereabouts)GHz system with 1GB of RAM and USB2 (no Firewire).

I see that there is a firmware upgrade for this drive, but I've seen some reports of serious problems if that is installed. I haven't yet downloaded or installed it.

Obviously, I'm doing something wrong. But what?