Yes, in my project there are many forms wait for the menu event to call them up.
The main.prg included the read event clause at the last line. And to my superise is it was all ok before last modification.
The windows did nonthing, and I could find the application in task list by press ctrl-alt-del, but no window came out to indicate it was running.
It's very strange. Could leave me more clue on that to solve the headache problem. Thanks.