2009-09-02 11:38:33 UTC
It sounds like the prefpane is not able to update your settings file for some reason, possibly unrelated to Snow Leopard. The settings file for the machine is /Library/StartupItems/DoubleCommand/DoubleCommand.pref - try changing this file to have only the number 0 in it, which will cause DoubleCommand to have no effect. This could just be a permissions problem.