USB Keyboard Amok?

[Petrus de Calguarium]

Hardware:

Logitech USB Keyboard
Asus Motherboard

Problem:

Approximately every 100th cold boot/system restart, the 
BIOS message, as it is displaying memory, hard drives, 
etc., is all scrambled, even in colour, and the beep 
that normally occurs at boot becomes a single long ring 
that never stops, and the system hangs, unresponsive to 
any input.

Solution:

To remedy this, one must unplug the computer, wait 
until the LED on the motherboard extinguishes, remove 
the battery from the motherboard, plug in a spare PS/2 
keyboard, put the battery and power cable back in, and 
reboot.

Then, the BIOS settings must all be set from scratch, 
as they are totally awry - no, not the defaults! If one 
does not use a PS/2 keyboard, no keyboard entry is 
possible. If one does not remove the battery, then some 
mysterious BIOS supervisor password will be set that 
cannot be circumvented (I don't use a BIOS supervisor 
password).

After having performed all of these steps, the system 
works perfectly, like before, until about the 100th 
time (wild guess - a long time - but often the problem 
occurs 2 or 3 times in a row, then not at all for 
weeks). Curiously, the same problem existed with a 
previous Asus motherboard (same USB keyboard, which 
works perfectly, as far I am able to determine from 
regular, daily use).

Is this an Asus problem, since 2 Asus motherboards are 
affected (I upgraded the BIOS, but there have not been 
any new upgrades available for 18 months), a USB 
keyboard problem (the problem occured on the older 
motherboard while kbd, not evdev, was in use), or 
something altogether different? I have been unable to 
replicate the problem or determine any actions/states 
that appear to produce it.