I noticed there was a thread earlier about a similar problem, but there doesn't seem to be any followup by the original poster.
I'm having difficulty with my left click button and it seems to be getting worse. It seems to have a "sweet spot" and if you don't click at that particular place, the button may register a double click instead of a single click or it may do nothing at all. A good, firm, uncomfortable click will usually register correctly, but it's not the sort of click you can do in a game for any length of time.
As I mentioned, this seems to be getting worse and worse. When I started using the mouse, back in January, it worked flawlessly, but it's going rapidly down hill.
Anyone else having this issue?