FYI if you're still looking into this, this comment helped me http://codebutler.com/firesheep#comment_5843350 http://codebutler.com/firesheep#comment_5843350 I

FYI if you're still looking into this, this comment helped me http://codebutler.com/firesheep#comment_5843350 http://codebutler.com/firesheep#comment_5843350 I have filevault turned on. Moving the binary out of my home folder (and adding a symbolic link) solved the problem.