Comment by monk_e_boy

I had a mouse that would stop working occasionally. The pointer would jigger and shake, or get "sticky" on some parts of the screen.

After a few weeks I narrowed the problem down, it happeneed in the late afternoon, but it worked fine in the evening. It also worked when it was raining.

So it had something to do with the sun shining through the window.

So I took the mouse apart and found that it had little rollers inside, each roller had a small black disc with holes in it. An LED one one side and a photoreceptor on the other... I assume it worked by counting the flashes of light through the holes in the disc.

The plastic cover on the mouse must be semi transparent and when hit by the sun, the photoreceptor was giving weird readings. I covered the mouse in black tape and never had the problem again.