>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.

Robin, since your last modification was to table structure. If you have the grid which record source is that table (or view from it) - check all column ControlSources if they are correct. It is often the case that the grid bombs if the column.ControlSource does not reflect the changed table structure.