I have had this problem occur 2-3 times since I have had my Curve. I tried many things - removing/cleaning the trackball numerous times, messing with the "copper spoon" as Thatzmister2 mentions above, full power off (battery removal) many times, even procured and installed a whole new trackball assembly - and none these worked. BUT what did seem to clear it up was when I "tweaked" the unit somewhat - i.e. wrangling it's neck, so to speak - by grabbing it length-wise in both hands and the clicking function started working again. This sounds crazy, but after exhausting all I could think of, I assumed something was wrong internally and had nothing to lose. Since the episodes of the of the non-functional clicking came about only after I would have my Curve in my jeans pocket while doing chores/work around the house, maybe the unit got messed up during that activity. I now only carry the unit in the holster and the clicking issue has not occurred again.