I recently installed Win xp pro in my computer (formated before installation) and after this usb ports are not correctly. There are 2 usb ports on the front and 2 on the back. When I plug in a device (mouse, keyboard, printer) for one port, it sometimes works and the next time I try the same port, it doesn't work. However, all 4 are never working at the same time. I tried to uninstall Usb root hubs in device manager in safe mode and to install them again, but this didn't help. I've also tried re-installing windows and windows repair, but the same problem occurs every time. I have a rather old Compaq presario computer (7el7000T) and was using Win Me before xp installation.