This usually happens when there is an Option, Switch or an Invisible condition specified for any Part or Line and the condition is based on the user input within the same form.
For example :
If user selects Bank Ledger, then display Cheque No. Field else make it Invisible. Hence, when the line is being removed or added, the entire form gets repainted as if we are entering this Report from a Menu Item.
The Solution to this issue is instead of having an Option, Switch or Invisible condition, set all the fields within the required line to Inactive based on condition. Here, the form need not refresh since there is no new line getting added or removed as the line is always available. Only the field contents are inactive.