Problems by viewing DVD's

[RiRa32]

Hello,

I have a lot of trouble playing DVD's - in 67% after 60 to 80 minutes my players don't like to play the dvd's any more: (media are quite hot after that time)
Funny: I have no problems with the combination +/- RW and Cyberhome -
is that because the media are "silver"?
There are also no problems with data dvd's only with video dvd's.

DVD Players:
Panasonic A7, Cyberhome 402 ,Toshiba 202, Yamaha ?
(Most problems with the A7 and Yamaha round 90% - less problems with Cyberhome 20-30%)

I am using Nero 6 with a Sony DR-U12A (500A) burner (Firmware: 2.0c which allows to burn 1x media with 2x and 2x with 4x)
and diverse DVD media:
- Verbatim -R (2x)
- Verbatim +R (2,4x)
- Ricoh +R (4x)
- Benq -R (1x)
- Memorex +R (2,4x) (very bad quality)
- Memorex -R (2x)
- Philips +R (4x)
- Verbatim +RW (2x)
- Verbatim -RW (2x)
- Intenso +RW (2x)

Any Idea how to solve that problem?
Is that a problem with my burner or with the media?

[CDRecorder]

How hot are the discs getting in your DVD players? That doesn't sound like it should be happening.