USB conflict - Keyboard and mouse - 8PE667 Ultra

I have a GA-8PE667 Ultra P4 motherboard.
All is hunky dorey, but just recently I decided to switch from the mouse and
keyboard both being on PS2 over to USB.
Installed all the necessary drivers etc and got into windows. The mouse
hadn't initialised properly (Yellow exclamation mark with a 'device cannot
start' error) so I had to manually install the driver and as soon as I did,
it worked just fine.
However, on every reboot I get exactly the same scenario. Keyboard is fine,
but the mouse requires to be installed on every boot - as soon as it sees
the driver it's fine, and no reboot is required. But it is a pain to have to
that manually.
So I switched the keyboard over to PS2, leaving mouse on USB - absolutely
fine that way.
But I want both on USB.
Is there any known cause of this problem, and any way I can remedy it?

P4 2.4b @ 2.7
8PE667 Ultra
2X256MB Crucial 266 DDR
Logitech Optical wheelmouse
Logitech Internet Navigator Keyboard

Windows XP Pro