High Pitch noise in audio

[Browncoat]

I've downloaded some mpg's of one of my favourite tv series which were not DVD compliant so I converted to compliant mpgs and burned to dvd, problem is now there is a distinct high pitch whine pervading some of the episodes. I dont think the noise exists on the original mpgs whose audio is 44KHz stereo, 224Kbps layer II.

Any suggestions?

[guns1inger]

How did you convert them ?
What tools did you use ?
What process or guide did you follow ?

[Browncoat]

I use PowerDirectorPro to make all my DVD compliant mpgs, and have done regularly for a good long while. It's only 2 recent particular episodes that have presented this audio anomaly, the rest are fine.