Mouse Problem

....need some suggestions for this one.

On a work machine running W2000 SP4, I have a new Logitech MX700 cordless, wireless, USB mouse. An idential one works great on my
home machine. The problem is that the mouse stops responding on occasion - the cursor won't move and the mouse wheel won't scroll.
After about 15-30 seconds, it starts working again, but will then repeat the problem a minute or two later. After about 5 on-off
cycles like this, it will work fine for an hour or two until the problem reoccurs. This has occurred with two different Logitech
mouse models and two different MX700 mice. It occurs regardless of whether the mouse is plugged into the USB connection (integral to
the Motherboard) or the PS2. The keyboard seems to function when the problem occurs. The IT people claim that the entire motherboard
was replaced on warranty, but the problem continued (I'm wondering if this was really done). They suggested an entire reinstall of
the OS. That still didn't solve the problem, which repeared after only minimal software was installed. I've already installed the
latest Logitech mouse drivers. The problem started when no Logitech drivers were installed. I've also noticed that although I have
set the mouse for very rapid motion, the mouse curser speed reverts back to the default speed when certain software is open (but not
other software). In other words, when the software window is open, the mouse moves slowly across this software window, but after it
gets to the desktop, it moves faster again - it only does this for a limited number of programs. All of this is quite annoying and
has baffled just about everyone I've spoken to.

Anyone have any ideas?

Thanks

Jeff