USB (Universal Serial Bus) is a popular plug-and-play hardware interface to use external USB devices like flash drive in your Windows XP computer. If you want to use an external USB device, you will have to enable the USB functionality in your computer. Check the steps given below and enable the USB port in a few quick steps: (See Also Windows XP support)
1: Before you begin, make sure that you are logged in as an administrator user to your Windows XP computer. Failing to which will not let you make any change to your computer.
2: Click the Start button> right-click My Computer> select Manage. In the Computer Management window, expand System Tools> click Device Manager> and then expand Universal Serial Bus Controllers. (See Also how to improve Windows XP performance)
3: Click the + sign to expand an item. Then right-click a USB Root Hub (you may see several of them) and click Enable. If prompted, confirm the action. If you do not see Enable option when you right-click the USB Root Hub, you may see Properties. Click Properties to get in the properties of the USB Root Hub.
4: Under the General tab, select Use this device (enable) from the Device Usage drop-down box at the extreme bottom. If you want to update drivers for your USB Root Hub, click the Driver tab and update them. When done, exit the Properties window and restart your computer. When the computer has booted, plug your USB device and start using it.
5: Alternatively, you can click the Start button> go to Control Panel to enable the USB Root Hub. Double-click Performance and Maintenance> open System to get into System Properties. Depending on your Windows XP version (SP2 or SP3), you may not see Performance and Maintenance but instead straightforward see System.
6: When in System Properties, click the Hardware tab> click the Device Manager button. Here in the window, you can repeat the third step to enable a USB Root Hub.
7: Another way to enable a USB Root Hub is by editing the Windows Registry Editor. Click the Start button> go to Run. In the Run window, type ‘regedit’ in the Open box and click the OK button.
8: In Registry Editor, expand the HKEY_LOCAL_MACHINE and navigate to SYSTEM> CurrentControlSet> Services. In the Services category, click usbstor. Look in the right hand pane of usbstor and you wil see the list of keys and entries there.
9: Double-click Start and change its value to 3 in the Value Data box. While changing the value, make sure that the Hexadecimal button is selected. Click OK to save changes and exit the Edit DWORD Value. Exit the Registry Editor window also and restart your computer. You can now start using your USB device. (See Also how to fix registry errors in Windows 7)10: If you face problems while enabling or using your USB port, contact Windows XP technical support.