The graphic is simply used as a diagram of the antenna that pictures the dimensions needed for the equations. I do mean that values are plugged into each field six times or so before the program hangs using the mouse to select each field. So, if the user does a lot of playing around with different dimensions and frequencies during the same session and uses the mouse to change from one field to another the program might hang.

Compiler: Visual Studio Standard Edition 4.0 Language: C/win32 My program uses 10 edit controls three of which are read only and 2 push buttons. I am using the tab-stop style controls. My problem is that when navigating the controls with the mouse the program hangs after clicking each input control about six times. If I navigate the controls with the tab key I don't have this problem at all. This program performs calculations for building an antenna for amateur radio use and includes a graphic of the antenna. EDIT: If I process WM_LBUTTONDOWN in the main window 40-50 times the program hangs. So it happens even if I'm not using the edit boxes. Sorry if I'm not making everything clear. The user enters values and then presses the calc button for one calc and does the same for another calculation. Two sets of edit controls and two push buttons.