Mouse cursor hangs very regularly

I know I'm a bit late, but owning two Evoluent Vertical Mice (models 2 and 4), I'm pretty sure I know what your problem is. In fact, it's a cable problem. Most Evoluent mice have the same problem, both of mine had it. The way the main cable passes inside the mouse, it tends to break from the inside after a couple of years of use. You will find instruction videos on how to fix this. I tried myself, and it works. For example:

https://www.youtube.com/watch?v=EE_Z-vXzDTw

If you don't feel like repairing it yourself or simply don't have the tools to do it, you can also replace the cable, and it's cheap. Here's a link sent to me by an Evoluent employee. He told me the inside connector is pretty standard, and it should work like a charm.

http://www.ebay.com/itm/FOR-New-Microsoft-Intellimouse-Explorer-IE3-0-Gaming-Mouse-Mice-USB-Line-cable-/161706519199?hash=item25a675aa9f

Hope this helps!