left-clicking on touchpad sensitivity

I have had problems with the left-clicking function of the touchpad.  I have tried adjusting the sensitivity either way in the Mouse window of the control panel, but it seems like no matter what I do, every single click turns into a double click.  This is frustrating, as when I want to close out one window,I end up closing not only that window, but the one right below it as well. Selecting a file turns into double-clicking it, which opens it up.  This happens regardless of what folder I am in, what directory.... with a variety of file types. Often, clicking on a box on a webpage will end up NOT selecting it, as the computer thinks I have selected, and then unselected it.  I have only noticed this irritating habit in the last few months....I've had this for over a year now and I'm generally very happy with this until.

Any suggestions? I already reinstalled the driver for my touchpad--from Dell's site.

Inspiron 1501

Windows XP SP3