Audio sounds like chipmunks when playing a DVD

[acz]

This problem is so odd, that I am almost embarrassed to post it, but it may give you chuckle, and I really hope someone has an answer, too.

On my very trusty and reliable old T61 (7658 CTO), running Win XP SP3, an occasional DVD is played. All the audio and video features have worked properly until yesterday.
Suddenly, the audio track from any DVD sounds like chipmunks!Each voice from the DVD is transformed into a much higher frequency. The video looks fine, the music speed seems normal, only the voices of the actors & actresses is changed.

In-browser flash videos are OK.
iTunes continues to play just fine.
Skype works OK to record and play back on a test call.
Thinkvantage Toolbox says OK to all hardware diagnostics.
Device manager has no exclamations or question marks, and the "SoundMAX Integrated Digital HD Audio" drive version is 5.10.1.5520.

I have not knowlingly installed any audio-related software.
Has anyone heard of this "squeaky" problem before?
Can anyone suggest a fix?
Thank you!

[RealBlackStuff]

Refresh or change the Codecs.
Also check the default audio selections, maybe yours was changed?

[acz]

Thanks but I have no idea how to access or change the codecs.
As far as I can tell, all the Sounds & Audio Devices that I can access from the Control Panel use the Soundmax HD Audio, and there are no other choices.

[acz]

I downloaded and reinstalled the Soundmax HD driver from the T61 device driver matrix, but that did not solve the problem.

Next, discovered that the Windows Media Player now shows the video part of a DVD but there is no sound at all. And a Warning box pops up which says,
"DVD playback is not enabled for this player.
Click [OK] to use InterVideo WinDVD Player for playback."

OK, so WinDVD does in fact play the DVD. I discovered that WinDVD has some sub-menus that appear when one clicks on the right-arrow icon at the far right edge of the WinDVD control panel. There are choices for Navigation, Language, Display, Color, and Audio Effect.

The choices in the Audio Effect submenu are

• Environment (Normal, Theater, or Late Night)
  DSP effect (None, Rock, Bass, Hall, Soft, Vocal, Echo, Karaoke)
  and then there is a slider which apparently shifts the speed of the speech...

so sliding that around solved the problem.

I think I have learned that DVD players have more features than I imagined.
Perhaps I will experiment with "VLC Media Player" or "GOM Player".

Hope this info is helpful to someone else.