Well, although I wouldn't use vista with an 1.7 GHz processor your laptop should be fine. And I've never heard of a bug like that. Please click on teh gears icon in the top toolbar of sed with the name "preferences" and ensure there is the file you want to run given under "Main Script to run / publish". A black engine window with nothing more is normally the result of an empty script. If that doesn't work, try a "printf("test");" at the very beginning of your main function. Is there then a message box appearing saying "test"? Also ensure you saved your file with the extension ".c".