MS mouse loses focus

[nuubie]

There is a very convenient shortcut I use all the time that replicates Command_W. Or Option_W I guess on Apple kb's. I use it on the wheel button so every time I need to close a window (hundreds of times a day) one little pop with my finger does it. Lately I've noticed that I have to do it several times for it to work. Other times it doesn't work at all. Yet Command_W always works flawlessly. IF the mouse was broken I think the operation would be more consistent. Any ideas? Is there any other way I get the mouse shortcut to work other than using the MS driver? Its called an INtellimouse driver. I don't trust it.