Mouse is double-clicking

I have an IntelliMouse Optical (USB) connected via a "data transfer switch"
(for using single set of kayboard, mouse and display with 2 PCs). The
connectors on this switch are PS/2, for the mouse I'm using an adapter
(suplied with the mouse).
I have installed IP5_2Eng.exe.

When I single-click on an object it is registered as a double-click, but not
alway, about every third or forth. It is annoying, really.

I've tried connecting the mouse directly on PS/2 of one of the PCs. Still
there. The switch is not a problem then.

Any idea?

Thank you.

This is an age old problem with Microsoft mice, ever since they first
started making them.

The problem is due to noise from the microswitch. It gets worse with
use, and the only cure is to replace the mouse. Microsoft are pretty
good about replacing them free if you send it back.

It's a design problem - there is no electronic 'debounce' on the
microswitches. This could be cured by redesigning the electronics, or
by incorporating software debounce into the driver.

For some astonishing reason Microsoft have done neither.

When it gets really bad you can generate whole strings of 'clicks'
simply by moving the button slightly when it's pressed down. Try it:
press and hold it down (so you've heard the 'down' click), then move the
button up and down just a tiny fraction - not far enough to get the 'up'
click. If your microswitch is really bad you'll be able to induce
double (or multiple) clicks to order.

Microsoft make excellent mice in every respect apart from this. Why
won't they fix it?

Steve