Strange optical mouse issue

I have an Mtek optical mouse, usb2.0, winxp pro and a7n8x dlx.

Everything works fine. However, I notice that the mouse pointer will occasionally jump to a random location, as if my system were remotely controlled.

I'm almost sure it's not a trojan or any other virus (yes, I'm connected 24h, no firewall, no sp1). Viruscan has found no virus.

Is this an optical mouse issue?

does it jump while moving?? or while the mouse is just sitting still? if its while your moving the mouse, then it might be your mouse

It jumps when I move it after it was standing still. Like if I was typing something then decide to move the mouse pointer, the pointer appears somewhere else, generally at the upper section of the screen. As I mentioned before, it's rare, but it freaks me out.

most optical mice use auto calibration software or drivers. When the cursor has been sitting a while, or was used alot, the cursor can "jump" to re-calibrate itself. I don't think its anything to worry about, my wireless optical logitech does it all the time.