Hi Phil - I'm really new to programming in QB64 (actually programming period). I had a similar experience with QB64 in that some of my programs were not handling the data correctly and, like you, there were no error messages. Eventually I discovered it was in the way the color was being treated. The programs were operating correctly but just weren't being displayed. Because you seem to be having difficulty with only 1/2 your programs, perhaps there is an algorythm which is common to those programs and not the other 1/2.