E520 Usb Keyboard And Mouse Not Working Dell Dimension E520 Windows XP Media Centre. Problems With Usb Keyboard & Mouse.?

Dell Dimension E520 Windows XP Media Centre. Problems with usb keyboard & mouse.? - e520 usb keyboard and mouse not working

I replaced the Dell USB keyboard with a standard USB keyboard, it works very well in the BIOS screen but does not function at all after the welcome screen, and my new USB mouse does not work so well. All ideas, no legacy support enabled in the BIOS and all USB ports are.