首先,這是因為第一版的WindowsXP並未支援EHCI控制器(也就是USB2.0)微軟是因為兩個理由而未支援:
1. There were no production quality EHCI 1.0 compatible host controllers.

2. There were not enough production-quality USB 2.0 devices for testing.
關於這點,微軟已經於SP1中加入支援.
其次,如果您安裝了SP1而還有以上情形者,微軟也提供排除錯誤的方式:
1. Open Device Manager. Locate Devices by Type.

2. Right-click USB 2.0 EHCI Host controller, and then click Update Driver.
You can find the USB Host controller entry in either of the following locations: • Universal Serial Bus Controllers.
• Other Devices
Note In the Other Devices location, the USB Host controller entry is labeled Universal Serial Bus controller with a yellow exclamation mark.

3. Click Install the software automatically (Recommended), and then click Next.
4. Click Finish when installation is finished.

Note You may receive a message to restart your computer to finish the installation.
最後,微軟再SP1之後也提供一些USB的更新檔,所以如果你還解決不了就裝SP2看看吧....
如果連SP2也不行,那就從硬體設定去排除吧