I have a command F3 "change grid form" in my form.
This command destroys all grid columns and then adds new columns to grid.

To destroy columns I use

  this.gridbase1.columncount = 0  && C5 error occurs in this line

I tried also

  DO WHILE this.gridbase1.columncount>0
    this.gridbase1.DeleteColumn   &&& C5 error occurs in this line
    ENDDO

Using those commands in VFP 7 will cause C5 error sometimes. This works in VFP 5.

Is there a way to re-create grid columns to avoid C5 error ?