General :: Module Crashing After Changing Window Mode In Macro

We have been calling a main form to manage yacht races using a hyperlink/macro from a selection form which lists all the yacht races ..The main form was too big to fit on some screens so we changed it to pop up mode to allow it to be resized and use scroll bars. this works well when the form is opened manually and all functions run just fine

the hyperlinik/macro for race selection had originally been set up to call the main form in dialog mode but we have had to change this as it disabled the resizing of the form and the scroll bars..The macro tool doesn't offer pop up mode so i selected window mode = normal and the main form opens with a resizable window and scroll bars but all the functions called from this module now fail (error message = use of null value or similar and all the functions go into debug mode - the server is down and i can't access the system to get the exact details)

If i change the macro in the selection form back to window mode = dialog the functions work but i lose the resizing of the main form and and the scroll bars.