My XPS 720 will not start if there is a device, in this case a wireless mouse pickup, plugged into ANY USB port. I have checked all the BIOS settings to no avail. I have looked under the Hardware Device Manager for conflicts...there are none. To start the computer, I have to take the mouse pickup out of the USB port, wait until Windows (XP- SP3)  loads and reinsert the pickup. Then there is no problem. The keyboard, btw, is also wireless with its pickup plugged into the first USB port on the back of the box. I might mention that both the keyboard and mouse are Logitech although they are not of the same 'set'. Keyboard is the S510 and the mouse is the MX1100. Any ideas out there?