After two months of working correctly, I am experiencing an strange and very annoying problem. My mouse pointer is moving on its own. If I move the mouse to the left, as soon as I stop the movement, the pointer runs again to the far right. This makes the mouse totally unusable.

The mouse device is an optical USB mouse.

It is not a problem with the mouse itself. I have tried with another mouse, same problem. (both mice are OK, I have tried both mice on my laptop, both worked perfectly)

Have tried different surfaces, too. Same problem.

System is Windows XP Pro SP3. Computer is a desktop PC two months old.

I suspected it could be a problem with the mouse driver. But both mice are from different brand, so I suppose they use different drivers.

What else can I try? any suggestion?