VFP3.0b for Windows.

I have a form with a grid which displays records that are filtered us a SET FILTER TO statement. The first time the form is displayed the filter works properly, but if I use the scroll bars on the grid the filter condition seems to be cancelled and all records from the table are displayed.

There is no code in the grid that removes the filter condition.

Some other info:
The table is opened before the form is run and stays open after it closes. The filter condition is set before the form is started.

Any ideas?