Try reinstalling - it sounds as if the path to the plugins has not been set correctly. Do you use Bryce 5.5, and launch D|S from within it? There was a problem a while back with that wiping the path information, though if it runs at all with D|S 1.0 on the system you should be up-to-date: still, if you haven't downloaded the Bryce 5.5 c update it may be worth trying.