Dell SX280 Upgraded now DVD Burner says DL disks "are not empty"

I hope someone can help.

I upgraded my trusty old (very old) Dell small form factor PC to Windows 7.

All seemed well, until I tried to burn a Dual Layer DVD+R with Nero.

I got the message that the disk is not empty.

Tried again with ImgBurn - same message.

I've tried lots of disks, same issue. Have over 500 to use up which is the problem!

Does work with a Verbatim SL DVD+R disk

It's a TSSTcorp DVD+-RW TS-L532B ATA Device

Anyone any ideas?

Jeff