"DVD brand: MEMOREX DVD+R 8X 4.7GB"
Mmmhh. Could indeed be your media. But don't panic yet.
I don't remember which app offers the "finalize disc" feature, but you can do it with Nero by simply burning some more on the disc and choose the "finalize" option while you're at it... even a couple of kilobytes will be enough!
If Nero refuses to burn more on the disc, this will mean you've actually finalized it and that your Memorex disc is not compatible with your Standalone player, or you had a bad burn with this disc on the Toshiba (2.4X speed with 8X rated media may or may not be successful depending on the media and the drive). These things happen....