Check that the consolekit service is also on at bootup. Besides that, the udisks, upower, consolekit, policykit and udev flags apply here. Check they are on, particularly for kde-base/kdelibs (emerge -pv kdelibs).
What kdelibs (and kde, in general) version(s) are you using? Hal hasn't been needed for disk mounting nor anything else for a long time. -- Jesús Guerrero Botella
