I just experienced this problem and went round in circles for a few hours before stumbling on the solution. My camera, a Sony Cybershot, has 4 USB Connect modes in the Setup menu: PictBridge, PTP, Mass Storage, and Auto. The only mode that would work to bring up the Camera Wizard screen on an XP computer was PTP. Once I changed the setting from Auto to PTP, the camera was recognized and able to connect to the computer. Somehow this setting had got changed to Auto or Mass Storage and that evidently causes a problem such that XP does not recognize the camera.
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.
Answers & Comments
I just experienced this problem and went round in circles for a few hours before stumbling on the solution. My camera, a Sony Cybershot, has 4 USB Connect modes in the Setup menu: PictBridge, PTP, Mass Storage, and Auto. The only mode that would work to bring up the Camera Wizard screen on an XP computer was PTP. Once I changed the setting from Auto to PTP, the camera was recognized and able to connect to the computer. Somehow this setting had got changed to Auto or Mass Storage and that evidently causes a problem such that XP does not recognize the camera.
Try 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.