Shouldn't hurt anything to go to the mfr's website and get the latest driver update and install it. Worth a go.

Possibly dusty, though the machine is only a few months old and what are tha chances of both lenses going crap at the same time. (there are two drives, neither works) No dvd works, so it's not a cleaning issue. Also if it was a dirty dvd or lens you wouldn't get a video signal. In this case the video is fine, just no audio on either drive, with any dvd.

Long before looking for a solution, first establish what is and is not working. Break the problem down into parts. Every responsible computer manufacturer provides comprehensive hardware diagnostics. Tests only hardware without any Windows or drivers to complicate the issue. If the hardware diagnostic test passes, only then move on to drivers, Windows, or media incompatibility. Remember there are numerous DVD R/W standards for the same reason why the silly 'Blue-Ray verses HD-DVD' war is ongoing.

Take it one step at a time. Do the computer hardware diagnostics report a good DVD and sound card?

Taking another tack. What is reported in Windows Device Manager? Does it show any problems with any other hardware? Also critically important information obtained before trying to fix anything.

Audio codecs are a possible point of failure, if DVDs use a different codec than CDs.

Ha! get out your tinfoil hats everyone.
Got through all the various steps of troubleshooting and this is what I turned up:
Hardware is fine
Media are fine
other playback software is fine
Following Dell's troubleshooting flowchart through removing and reinstalling just about everything on my computer, I finally got to the part about downloading the latest version of DirectX software.

When I tried to do that, I was confronted by Microsft's gatekeeper informing me that before I could download DirectX they needed to check my Windows Genuine disAdvantage spyware, I mean software.

The upshot being that I could not upload the new version of WMV since I do not have their spyware installed.

Now that I have remove wga software, I'm tempted to intsll install it just to downlaod the new directx, then ditch it.
In the meantime our 15 yearold babysitter/mathgenius/computerguru had me download VCL which works fine and is free and all that stuff.
[/conspiracy theory]

I just keep wga blocked with McAfee until I need it. ;)