You really need to look at what you are doing while using the mouse.

Some of the most common causes of this problem is large breasted women leaning on the touch pad or keyboard, the users non-mouse hand leaning on touch pad, keyboard or graphics tablet or the family cat is asleep on something important.

So do you lean on anything with your non mouse hand while using the mouse????:^O

(I dare not ask if you have a large rack:^O)