The Punk - I am using Moonbase Alpha b_V5a. I switched off all visual parameters and reduced the video size to 800 x 600. Then all the Moonbase Alpha and Eagle II scenarios began to work. This seemed to imply that there wasn't enough processor speed/memory available. I restarted Windows Vista with fewer programs running in the background. Now I have restored the visual parameters and video size. All seems well. Thanks for your interest. I couldn't have suceeded without your help with editing the config files.