Hi I have a Microsoft Comfort Optical Mouse 3000 which has always been extremely useful because of the Magnifying function that I occasionally use. Now though, when I activate this, the magnification is enormous and furthermore the screen jumps around erraticlly, and it is impossible to read anything. This mouse is still available so I am wondering whether to buy a replacement. I also understand there is an updated version the 4500 Model though when I read the spec of this, I did not notice anything about it having a magnifier. Has anyone experienced this problem with the Optical 3000 and if so, is it something that can be corrected??