Will not charge

have you tried charging it by plugging in with the interface. able to a compter usb port? Or if this is the method you have tried, try plugging it in to your car power source. If it still won't charge the internal battery may need to be replaced.

That's an odd one for sure, but it might be some safety feature so DRIVERS won't use it while driving.
The cheap solution is a 7812 votage regulator - but since the safety circuit is likely in the cigarette plug itself, it's not easy to put the regulator between the source voltage and the circuit input.
So, here's the not-so-technical solution.
http://www.tigerdirect.com/applications/SearchTools/item-details.asp?EdpNo=6421307&CatId=237
It's a 100W power inverter with USB
For under $20, it turns your cigarette lighter plug into a 120V AC outlet plus has a USB 5V port for things like MP3 players etc that charge off the USB port in the PC.
So basically you just plug in the home adapter into the 120V outlet, and you can watch and charge while driving. Not only that, it'll be good for other low power devices later on, not just this one (like laptop/notebooks blackberry/cellphones, any low power plug in device).
For the price, it's a perfect solution, and you can order online and have it delivered!

Wait for the battery to fully recharge, The battery was ln a low state, are you sure you were using the correct USB cord. Some look very similar but one of the inner cables is disconnected and so does not charge the unit.
If you still get no luck after using correct cable then it may be time to change the battery as it has collapsed. batteries last up to 2 years and can go very quickly. Never plug it into car power whenhj starting engine. It shortens battery life and damages siirf chip

Please rate my help++++Thanks for using FIXYA

They can only charge thru the USB port when your computer is on.There is no voltage supplied when it is off.This help?

If you can turn your player on while being plugged to your PC/Laptop or USB charger, then your internal Lion battery is most likely gone past its useful life (some 500 charges or 18 months usage) and may need replacing. Most MP3 player may show 'fully charged' when plugged in either when the battery is truly fully charge or defective battery is no longer taking a charge: e.g. minimum or no current flow situation.

I had the same problem this morning, albeit with my 8G Clip. Nothing worked -- the thing seemed dead as roadkill -- until I found a link about "forcing MSC mode." Basically, it told me to hold down the center button while plugging my Clip into my computer using my USB cable. Suddenly, boom! It's awake and alive and happy again. I'm unsure how that works, but that did it for me.

Check the connector of the USB Ports and Sony. Also it's internal battery require replacement.

I just called tech support at 1-800-800-1020 and I was told that the battery on the unit may be so low that it won't power on even with a power source. The unit actually uses more power than it's taking in from the car charger. I was told to plug it into the computer using the USB cable and give it a few hours to replenish the battery. Apparently it should be plugged into the computer ever so often to keep the battery from getting too low.

Try getting a new USB Cable.
I myself have had the Same Problems.
And that seems to help.

did u try to charge it connected to your pc? maybe its the charger