This has been broken since .0 for me, but I haven't really cared until now. Checking the File Sharing option in System Preferences would cause the box to instantly untick itself. I then enabled SMB which allows the File Sharing toggle to work as it should, but it only enables SMB. If I tick the AFP tick box it half ticks (comes up as a hyphen [-]) then instantly unticks. I've tried rm-img ~/Library/Preferences/com.apple.systempreferences.plist and com.apple.systempreferences.plist.lockfile, which didn't revert anything in SysPrefs. Unfortunately all the info I can find on AFP on Lion is about the issues with NAS support (or something). Any help is appreciated.