Is your PC up to date?
You may have to do a bit of updating by installing the latest service packs since MTP devices are buggy in early versions of XP.

Also issues with WMP11
below from: Readme for Windows Media Player 11 for Windows XP

Device not recognized after installing Windows Media Player 11

Some devices that support the Media Transfer Protocol (MTP) might not be recognized in Windows Media Player 11 for Windows XP.

If you encounter this issue, perform the following procedure.

1. Uninstall the device in Device Manager by performing the steps in Issues with devices after removing Windows Media Player.
2. Disconnect the portable device from your computer.
3. Reconnect the device to your computer.
4. Start Windows Media Player 11 for Windows XP and verify that your device is recognized and displays in the Player.

Phillips Gogear
you can resolve these issues by rolling back to Windows Media Player 10, and then reverting to the Windows Media Player 10 version of the MTP device driver. To do so, perform the steps in Rolling back to a previous version of the Player, and then perform the steps in Issues with devices after removing Windows Media Player.