>I know that this error is probably being caused when a combobox's or listbox's rowsource is a SQL query, and the query is re-run without the RowSource being temporarily set to "". Problem is that the error seems to be occurring somewhere in VFP's innards, so it is not being trapped by our error handler. Is there any way of forcing this error into our error handler?
>
>--Peter Silverman, Insurance Data Processing

I've had this error without any stuff like this - the rowsource was a p-view, rowsourcetype 6 (fields) and it was open before the combo would initialize. The error (or rather, the message) was popping up only on the first activation of the page (this was on a pageframe) where the combo was. There were maybe six other similar combos elsewhere, and only this one had this error. The cause was a mistype in the controlsource, the last character was missing. I would expect any other error, even 'unbinding control' or something like that. Now since it happened only on the first refresh (and page3 doesn't get refreshed until activated) it gave this message instead. It most probably did unbind the control, but sent a different message, which was confusing me for days.

Of course, once I fixed the typo, the message vanished.