The final version of After Dark was engineered to run on anything up to 8.6, stock, but not all the available AD modules will work. You have to check and weed out the ones causing a crash.
One interesting thing is that installation of all available Quicktime upgrades, without further System software upgrades, gives radically different effects in some of the modules, at least in 7.6.1 and 8.1 (e.g., Marbles becomes a very different AD module).
What AD version are you trying to use?