Thanks for the reply.
Firmware is up to date, I downloaded the most recent update from memorex last week trying to troubleshoot my dual layer issue-- that helped with Nero, but I was still at 50% success.
The DVDs are Fry's brand GQ (Great Quality), which are my only affordable dual-layer option (15 for $16.50). I felt really good about the first DVD burned with Imgburn, it worked like a pressed DVD, no extra time or noise from my player to load. If it's just the discs I'll have to wait for the price to come down and try again, but the first burn was perfect, and the next 4 have had the exact same error come up at the layer break. Seems like I'm not doing something it needs to at least attempt to burn the next layer.