Have you tried other USB ports? Will other USB devices work on the port you normally use for your camera?
Generally, you might have better luck using a USB card reader rather than connect your camera directly to your computer. If your camera uses xD cards, I suggest this card reader:
Olympus USB 2.0 xD-PictureCard Flash Memory Card Reader MAUSB-500 (White).
I have an older Olympus card reader, model MAUSB-200, and it works well for me for the xD cards I use with my Fuji camera. One advantage of using a card reader is that you never need to worry about your camera battery running low when you connect your camera to the computer and transfer pictures. If you're not familiar with card readers, when using one, you remove the memory card from your camera, insert it into your card reader, and then connect the card reader to the USB port on your computer.
Oh, I see Allan's solution worked for you. Still, I recommend getting a USB card reader.