I've seen a lot of posts about this auto-change whilst searching for solutions for this (and they don't know the cause) and I still can't find a solution to stop the auto-changing from the normal setting to the high sensitivity setting.
I have come to realise after using and putting up with the auto-change that the auto-change is caused when you hold down the left and right mouse button at the same time for a few seconds. This is actually a pain in a first-person shooter when you're holding down the aim button (usually right button) and shooting (left) and shooting a moving target because all of a sudden your sensitivity gets pumped up and you end up missing, forcing me to press the square button in the middle of the mouse.
I've seen topics for World of Warcraft with this problem too, about it changing - I like to move about by holding down both the left and right button, but I try to avoid doing that now because it'll ramp up my sensitivity
If anyone knows a solution to this auto-changing problem (and it works!) i'd be extremely grateful.
Thanks.