I can surfing and the mouse cursor will abruptly move to the far left of the leftmost screen. This can happen even if my hand is not on the mouse.
The mouse will also turn off at random intervals, requiring that I unplug and replug it in. (Mouse is a standard microsoft usb corded optical mouse with scroll wheel)
Both problems are happening more frequently, the mouse jump several times an hour, the power off several times a day.
Hardware Mac Pro 2012; Yosemite current.
In my search I've found other people who have this problem, but so far have not found one that either explains it or provides a solution.