I'm having the same problem.
I just bought some Verbatim 8x DVD+R DL discs, and they burn fine at 2.4x using Nero Express with a BenQ 1655 drive. I've ripped with DVD Shrink, DVD Decrytper, and Nero Recode. Not one DVD will play in my Panasonic DVD-RV41 standalone or in my PS2, but my BenQ drive reads them all fine.
I bought the Panasonice DVD player in 2000, so I may be out of luck here. All of the single layer DVD+R discs I've burner, either Taiyo Yuden or Verbatim Lightscribe, work no problem.
I just got the latest firmware, and I'll check the bitsetting. If those don't help, any other suggestions? Perhaps different burning software?