>>It looks like you are doing this with code when you stated "Set order to (blah)".
>
>No, when it crashes, the debugger Trace is on that line which, I presume is a standard component of the DE class.

So this is a DE class that you created and have in a VCX that you have defined for use by this form? If so, is there any code in your DE class? I am not aware of ANY code that would be visible in the debugger for events being fired internally by VFP. So any code you are seeing should be developer code from somewhere.