At random times about once every 5-10 minutes (and sometimes more frequently) my character's aim will move randomly and nearly instantly to a new position. The movement is horizontal, vertical, or both with varying degrees of severity. Sometimes the aim will jump vertically between 40 and 90 degrees, others the aim will move horizontally as much as 180 degrees, leaving the character moving in the opposite direction.

This issue occurs without any user input, and even while running in a straight line while freelook is activated (meaning that any mouse input is controlling head look, not aim.)

This issue is separate and possibly unrelated to other mouse issues such as odd mouse acceleration, which has already been reported extensively.