Will the app sometimes loaded with other conditions (perhaps not complete for testing reasons) or without any data or will the app saved although the loadscript failed with error? It means that sometimes this field is not exist.
... mmmh. You could look in the logfiles from server and app and perhaps you stored/extract this meta-data structure with every load/save. Important is to find when it happens to search any abnormality.
Sometimes a qvw is simply corrupt and newer one worked fine. Is the app not very complex, such a step with manually copy/paste could easier and faster as my first suggest.
I have an issue similar to Azimabadi: in this case what I often lose is a variable. In my document I've a "menu" that is managed though a variable (I set it in the first script) and therefore with an "Activate Sheet" trigger. No script errors (it happens by the client and I've managed to check for loading errors), no reduction , no test.
I'm using QDF so now I'll try to define the variable through the VariableEditor tool.
