预览报表错误?????!!!!!

[ably]

DELPHI4.0 当多次预览报表(quickrep)时(如15次)，出现如下错误
metafile is not valid
canvas does not allow drawing
out of system resources
需退出软件后再进入，则预览9次出错，以后逐次减少
有时错误造成需重新启动计算机,才可预览,救救这个可怜的程序吧！！！
附∶预览程序
with TwtPrvform.Create(Application) do
begin
wtQRPreview.QRPrinter := TQRPrinter(Sender);
CurRep := quickrep1;
Show;
end;
调用程序
with Trptform.create(self) do
begin
QuickRep1.print;
QuickRep1.Free;
free;
end;

[zcw]

with TwtPrvform.Create(Application) do
try
quickrep1.Preview
finally
free;
end;

[dragongong]

就这个程序来说 要加上:
procedure TwtPrvForm.FormClose(Sender: TObject; var Action: TCloseAction);
begin
action:= caFree;
end;