Have you tried another mouse?

Is your mouse wireless? Wireless mice are not the best for gaming as they are prone to interference from other radio signals and from electrical appliances. If it's a wired mouse you might check the cable for signs of ware or pet damage. You should also check to see if the batteries are still good.

Optical mice do not require a mouse pad but they do require some sort of pattern on the surface you are using it on and the surface should not be reflective. On a reflective surface or one without any sort of pattern you may get some annoying pointer jumping such as you have described.

The last thing I can think of would be an intruder who has the ability to control your mouse. If you have a firewall then you can just about rule this one out. However if your firewall only monitors and blocks incoming connections it's still possible for a trojan to connect out through the firewall to a third party computer bypassing your security measures.