There can be a series of issues here so I'll list a few and tell you how to solve them, you should be the judge and decide which one's you want to try:
Drivers - try disabling Synapse 2.0 and uninstalling mouse drivers (afterwards restart the computer). You have to disable synapse because it will always update and restore to the previous version of drivers that may or may not be faulty. Try asking WINDOWS themselves to find the appropriate drivers not Synapse 2.0.
Possibilty that Snap To is enabled - if it is, disable it.
Quoting from a different place: "It happens to mine all the time. Someone once told me to leave it along and let it move until it stops. I do that whenever it happens and it seems to fix itself."
A virus? - scan the computer just to be sure but I doubt it's this.
If you're using a USB hub, plug the mouse straight into the I/O.
Disable pointer precision under CP -> Mouse -> Pointer Options (same place where Snap To is).
I assume you don't have a touchpad....
Try turning down the DPI of the mouse in Synapse 2.0. Razer mice are very sensitive to vibrations (sub-woofers on the table, fans, hard drives, etc).
It doesn't hurt just cleaning the equipment AGAIN, grap a Q-tip for the sensor, clean the mouse pad.
Try the mouse in USB 2.0 not 3.0.
Maybe the cord is pulling the mouse sligthly?
Try the mouse at school/college/uni/work and see if the problem persists.
That's all I could find, hope something works if not, we'll try something else Good luck!