procedure TForm2.Button2Click(Sender: TObject);
begin
  pFIBDataSet1.DisableControls;
  try
    pFIBDataSet1.CloseOpen(False);
  finally
    pFIBDataSet1.EnableControls;
  end;
end;

procedure TForm2.pFIBDataSet1BeforeOpen(DataSet: TDataSet);
var FieldDef : TFieldDef;
      fldNew : TField;
      i : Integer;
      is1 : Boolean;
      ds : TDataSource;
begin
  TpFIBDataSet(DataSet).Prepare;
  DataSet.Fields.Clear; //Очистка полей [color=#FF0000]<- Тут происходит зависание[/color]
  for i := 0 to DataSet.FieldDefs.Count - 1 // Пересоздание полей по умолчанию
  do begin
    FieldDef := DataSet.FieldDefs.Items[i];
    fldNew := FieldDef.CreateField(DataSet, nil, '', false);
  end;
end;

procedure TCustomDBGridEh.Notification(AComponent: TComponent; Operation: TOperation);
var
  I: Integer;
  NeedLayout: Boolean;
begin
  inherited Notification(AComponent, Operation);
  if (Operation = opRemove) then
  begin
    if (AComponent is TPopupMenu) then
    begin
      for I := 0 to Columns.Count - 1 do
        if Columns[I].PopupMenu = AComponent
          then Columns[I].PopupMenu := nil;
    end
    else if (AComponent is TCustomImageList) then
    begin
      if TitleImages = AComponent then TitleImages := nil;
      for I := 0 to Columns.Count - 1 do
        if Columns[I].ImageList = AComponent then
          Columns[I].ImageList := nil;
    end else if (AComponent is TScrollBar) then
    begin
      if VertScrollBar.ExtScrollBar = AComponent then
        VertScrollBar.ExtScrollBar := nil
      else if HorzScrollBar.ExtScrollBar = AComponent then
        HorzScrollBar.ExtScrollBar := nil
    end else if (AComponent is TDataSource) then
    begin
      for I := 0 to Columns.Count - 1 do
        if Columns[I].DropDownBox.ListSource = AComponent then
          Columns[I].DropDownBox.ListSource := nil;
      if (FDataLink <> nil) and (AComponent = DataSource) then
        DataSource := nil;
    end
    else if (FDataLink <> nil) then
      if (AComponent is TField) then
      begin
       // [color=#BF0000]if FDatalink.Dataset.ControlsDisabled then exit; [/color] //Решает проблему но какими будут последствия?
        NeedLayout := False;
        for I := 0 to Columns.Count - 1 do
          with Columns[I] do
            if Field = AComponent then
              NeedLayout := True;
        if NeedLayout then
        begin
          BeginLayout;
          try
            for I := 0 to Columns.Count - 1 do
              with Columns[I] do
                if Field = AComponent then
                begin
                  [color=#FF0000]Field := nil;[/color] // проблема где то здесь
                  //NeedLayout := True;
                end;
          finally
            if Assigned(FDatalink.Dataset)
              and not FDatalink.Dataset.ControlsDisabled then
              EndLayout
            else
              DeferLayout;
          end;
        end;
      end
    else if (AComponent is TDataSet) then
    begin
      CheckIMemTable;
      if ViewScroll then
      begin
        UpdateRowCount;
        MTViewDataEvent(-1, mtViewDataChangedEh, -1);
      end;
      LayoutChanged;
    end;
  end;
end;