in the 1st time I ask this question and got this reply.
Did it just start after functioning normally? If you've changed any of your mouse settings lately that might be causing it. If the click speed has been changed to something you're not used to that might cause it. You can change your mouse click from double click to single click. Just go to Control Panel>Folder Options>General then select "Single click to open an item." You might try that. If it fixes it then you'll know it has something to do with the mouse's double click settings. Also, if you move the mouse even slightly when you're clicking that will cause it to not work.
the last line maybe the problem. I am on a lot of medication and some times my hands shakes quite a bit and they have been changing a couple of them in the last couple of months. I bet that is the answer. thanks Sharon