In other words, those are all the specs I know, what else would you need? I don't think it is prefs, as this has been consistent since about September, though I will delete them to be sure. I'm aware that you said you weren't sure, my question is can you find out what they are? Download this http://www.cpuid.com/ it will tell you what they are. It's hard helping someone if you don't have their specs. Are you sure that's for Mac, because PC wizard, which it seemed was the one I should use, said Windows 7/Vista. Tonka, I'll try that, I'm assuming you mean uninstall X-Plane, remove the disk, re-install, or do that with the disk in? Sorry I forgot you were on a Mac. And what Tonka means is download the X-Plane Demo from the X-Plane website rather than uninstalling your whole XP install.