How to eliminate pointer drift?

Hi

I have recently bought a Creative wireless optical 5000 mouse. I am having a lot of problems with it. The most infuriating is that the pointer drifts up and/or across the screen.

The correct driver is installed, and I have tried a variety of surfaces – standard mouse mat, matt surfaces, shiny surfaces, card, paper – all the time the pointer drifts. It is driving me mad!

Does anyone know of anything else I might try to resolve this please?