I downloaded the SL version, and I guess it's crashing on startup, since nothing happens when I click its icon. I tried renaming the Airport Module as suggested, although I didn't have a File Tagging or Services item in the plugins folder. After renaming Airport, I got the transparent QS logo thing that appears in the center of the screen at startup, but it still doesn't truly start up.
I did completely remove my original version of QS before installing. Is there anything else to try?
