Microsoft wireless optical mouse problem

Hi,

I've just installed Microsoft's wireless optical mouse
special edition with Intellipoint 4.1. Most of the time
it works OK but sometimes the pointer moves slightly the
wrong way initially. Sometimes the pointer jumps to a
different part of the screen when I've only moved the
mouse a little.

I've tried it with the USB connection and the PS2
connection. I've tried changing the radio channel. The
receiver is positioned at the right distance and away from
things that might cause interference. I've tried it with
two different mouse pads.

I'm not sure if this is a problem with the wireless part
or the optical part. Any help on this would be
appreciated.