I have multiple MS 3500 mice and multiple PC computers and a MacBook Pro. The mouse jumping around had occurred multiple times and I just replaced it with one of my other mice and then purchased another 3500 mouse. Today it happened again and I took the mouse off of my Mac and problem solved. I went into the other room and got the mouse off of my newest PC which had started acting up while I was in the process of setting up and had to put the computer aside for a while because of the need for the space. I had just left the mouse with it. I am a contract mechanical engineer and use CAD at work. I always travel with a MS 3500 wireless mouse and have had a few quit on me. I would replace it with a new one and go on. The last time it happened, I threw the old mouse in my equipment box and it is sitting near me right now. As the mouse I was using now on my desktop PC started with the same problem, I reached over to the Mac mouse and put it on and the problem went away, but I turned the old mouse over and noticed the blue light was flickering. I looked at the one now being used that I took from the Mac. The light was steady. I went into the storage room and picked up the mouse on the new PC I had been setting up when it developed the mouse problem. Turned it on and the light was flickering. I went over to my box with my equipment where I had thrown the mouse I was using at work when it went bad and the light on it was flickering. On the three that went bad, the light flickered. On the two that work, the light is steady. The mice are DEAD!