Problem copying DVD with Roxio Burn 1.0 on Dell XPS

I have a fairly Dell XPS Home Premium Windows7 64 bit PC.

It comes with Roxio Burn 1.0, but I cannot get it to copy DVD-R’s.

I can burn audio files to a DVD-R and play them.

The DVD-R was created on our DVD recorder and Finalized.

Roxio reads the DVD-R and pops out the disk and asks for “a blank, readable, DVD+R (recommended)”.

I put in a DVD-R, or DVD+R and it reads the disk and pops it out with the same warning. These are new Memorex disks.

I did a chat session with Dell Support and they could find nothing wrong. The Dell rep asked me what type of disks they were (Memorex) and later said that Memorex has known problems and that I should try Sony.

I happened to have one Sony DVD+R, so I copied the Memorex DVD-R, then put in the Sony DVD+R. It started to burn, but then reported a different error.

I had some blank Sony DVR-RW’s, so I put some video on one, and tried to copy to the other. It failed with “Device Error” and Roxio disappeared.

I tried InfraRecorder clicked on Video Disk, tried copy to Disk Image, and got “Cannot read TOC header”.

Any suggestions/ideas on what is wrong here (Roxio, my DVD recorder, Memorex disks) or what to try next would be very much appreciated.

Thanks