You wrote DVD player so I guess you have a MkIV unit...

The clue is to writ SLOW to the disk (preferably 1X) but as slow as possible. If you use "ImgBurn" (recommended), use the "VERIFY" function to be sure that the disk is written correctly.

If the disk is to be read in a MkIII or earlier the disk MUST be written in MODE2. The MkIV can read a MODE1 disk, but not the MkIII...

Start this way and then you can successivley increase the writing speed.
I have successfully written disks in 48X, but all CD / DVD writers doesn't do a good job on all types of media.

I'm using a Plextor writer and quality media. (Sony, Verbatim, etc..)

You are not just copying the .MDS and .MDF files to the disk, are you???
You MUST write using an "Image writer" software such as ImgBurn or Alcohol 120%

///M