Tinny sound on DVD playback

[wrighty2003]

I've just acquired an Asian copy of the X-Files Seasons 1-7 from e-bay and although the picture is fine the sound is tinny and a little annoying. I'm playing the discs back on an APEX-1100WB DVD player and do not have any problems with other discs.
Have I simply been duped on this i.e. the discs have been created wrong or is there anything I can do to improve the sound ?
It's a little frustrating when the seller has assured me that these discs are "genuine DVD's".

Thanks in anticipation.

[cplevel42]

I'm pretty sure that those DVDs were NOT official. A lot of the ones coming out of the Asian market are not.

OK, it sounds like the mpegs that were used to make those DVDs were encoded at 44100 HZ and not 48000 HZ like they should have been. I'm pretty sure that this is the problem.

Can anyone else offer any explanations?