>>P.S. This is the fourth modal form popping up in a chain of drill-down forms.
>
>More testing and more info:
>
>I tried various other windows and found Messagebox() does not cause the error (maybe because it's really a Windows API call or something outside VFP rendering responsibility), but other renderings, like WAIT WINDOW or DO FORM SomeForm will cause the same error.
>
>So, it's not necessarily the .Show of that particular form, but rather the rendering of ANY form at this point.
>
>Example:
>

>MESSAGEBOX( loNewObj.Name)   && this works
>WAIT WINDOW loNewObj.Name    && this does not
>DO FORM testform             && this fails too
>loNewObj.Show                && the original failing code
>

Maybe you're just pushing the Fox to its limits - showing fourth modal form in a chain. How about just reworking the whole thing into a single wizard-type form, using a tabless pageframe? Your chain of modal forms becomes a chain of pages, with far less of frame-level overhead.