I've had mice problems in WoW. I have a mighty mouse, and it's useless in WoW as you can't press both right and left buttons at the same time.
Is your mouse optical? Do you have a mouse pad? Funny, because I used a damp cloth yesterday to clean my mighty mouse. I thought I busted it, as the cursor started getting jittery and flying all over the screen when I moved it. I tried different USB ports and it still happened. So I took the mouse to the Apple Store, plugged it in, and of course, in front of the genius, it worked just fine and I looked stupid.
Brought it back home, and it didn't work on my imac! I thought something was wrong with my USB ports. Turns out, the National Geographic mouse pad I just got was "incompatible" with the mighty mouse! The reflective surface of the pad must confuse the optical sensor.
If it's not your pad, try changing you mouse settings in System Preferences. Log out and it again, and try it with a different account too.
