After using LCC for at least two years with older versions, v2.1 crashed when I tried to configure the wireless keyboard. That made me use the awful wired Mighty Mouse that came with my MacPro for a while. The cursor on that mouse jumps all over the place - but I digress. I used the guidelines mentioned by MacGuruGuy and manually checked that all Logitech and APE files were deleted. The LCC uninstall leaves several files behind. I deleted them all, installed the new v2.1.1 and restarted. I was able to configure the keyboard and mouse and am ecstatic to have them back.