Is it necessary to load the battery (power supply) when the camera is connected to the computer via USB cable?

When you connect the USB cable from the camera to the PC, the camera should shut down. If it doesn't perhaps your cable is defect. Or one of the connectors, from the camera or from the PC.
When the cable works on another PC (or Laptop) you can assume the cable is good. But then the USB connector in the PC could be not connected, or the USB controller in the PC is not working correct.
Sure you did install the Nikon software on the PC to?

Follow this order:
when plugging in the camera and then plugging into the compuer does the computer recognise it? If not this is either a bad cable, or not an active USB port, or something has gone wrong interanlly with the camera. Internal can be anything from bad voltage chip to bad battery. But some people have put the battery in backwards or with the positive terminal the wrong way. Double check that this has not happened, as anyone could have done it, unless you live alone. Try another computer and see if it recognises that camera if so the cable is good and you can continue to trouble shoot in other areas.

The battery itself won't charge in-camera like a cell phone-- you'd need to remove the battery and plug it into the supplied charger (EH-68P). You may have an ac adapter for the camera that basically would just be used to power the camera without a battery or for long periods of time without relying on the battery. It wouldn't be used to charge the camera.

You might want to consider NOT connecting your camera to your computer.

The best way to download pictures from your camera to your computer involves removing the memory card from the camera and plugging it into a card reader (either built-in to the computer or connected via USB or FireWire). This is likely to be faster than connecting the camera to the computer, and won't run down your camera's batteries.

Once the card is plugged in, it will appear to your computer as a removable drive. You can use the operating system's drag&drop facility to copy pictures from the card to the computer's hard drive, the same way you copy any other files. Or you can use any photo cataloging program.

Hi either direct from your camera via usb cable provided you have loaded the software that should come with the camera or via a card reader.

Consider NOT connecting your camera to your computer.

The best way to download pictures from your camera to your computer involves removing the memory card from the camera and plugging it into a card reader (either built-in to the computer or connected via USB or FireWire). This is likely to be faster than connecting the camera to the computer, and won't run down your camera's batteries.

Once the card is plugged in, it will appear to your computer as a removable drive. You can use the operating system's drag&drop facility to copy pictures from the card to the computer's hard drive, the same way you copy any other files. Or you can use any photo cataloging program, such as Picasa ( http://picasa.google.com ).

No. Connecting the camera via USB drains the battery faster.

How old is the battery? If the battery is refurbished or old it might just not charge anymore.

Also, do you have a separate charger for the battery? Many cameras do and that is how they charge, not when the battery is still in the camera.

Depending on the method you're using, this can usually be remedied in one of two ways:

1. USB Cable: make sure your camera is turned off before connecting to the computer, and that the drivers for your camera have been loaded prior to connecting.
2. Memory Card: SD or MMC card readers are becoming more std. on computers, or inexpensive card readers are available to connect via USB.

If you are experiencing difficulties with either of these, this may involve a problem with your USB port or the drivers your computer is using. Sometimes it's as simple as removing the driver which isn't working properly and re-installing it again. In most cases, you will need to install the driver without the USB device connected, so that after you have successfully loaded the driver, the computer will recognize your USB device properly.

Once again, make sure your camera is turned OFF when you connect it to your computer with the USB cable (of course, your computer needs to be turned on). Then, turn the camera on, and you should see the computer recognize the device.

Very few cameras will charge through USB ports. This is only to connect to computer to access pictures. Your camera will not charge via USB. I suggest to many people that using cameras that take AA batteries is the best cameras to buy when traveling. Many camera owner fall victim to different voltage outlets when travelling.