小弟我在关闭小弟我的程序之后(小弟我的程序是多线程的),出错

我在关闭我的程序之后(我的程序是多线程的),出错!
我在关闭多线程程序之后,系统出错:
1.Exception EOSError in module project1.exe at 0000E3Ae.system error code:1400 无效的窗口句柄.
2.Runtime error 216 at 7C921010

以下是我的代码:
unit UMain;

interface

uses
  Windows, Messages, SysUtils, Variants, Classes, Graphics, Controls, Forms,
  Dialogs, DB, ADODB, Grids, DBGrids, StdCtrls, ExtCtrls,excel2000,OleServer,comObj,
  DBGridEh, Unit2;

type
  TMain = class(TForm)
  ADOQuery1: TADOQuery;
  DataSource1: TDataSource;
  DBGrid1: TDBGridEh;
  SaveDialog1: TSaveDialog;
  Panel1: TPanel;
  Button1: TButton;
  OpenDialog1: TOpenDialog;
  Button3: TButton;
  ADOQuery2: TADOQuery;
  Label1: TLabel;
  Edit1: TEdit;
  Button2: TButton;
  procedure Button1Click(Sender: TObject);
  procedure FormCreate(Sender: TObject);

  procedure Button3Click(Sender: TObject);
  procedure Edit1KeyPress(Sender: TObject; var Key: Char);
  procedure Button2Click(Sender: TObject);

  private
  procedure ThreadDone(Sender:TObject);
  { Private declarations }
  public
  { Public declarations }
  ExcelToSQL:ImportExcel;
  end;

var
  Main: TMain;

implementation

uses UDM, Unit1;

{$R *.dfm}

procedure TMain.Button1Click(Sender: TObject);
var
fname,moldid:string;
excelid:variant;
ColumnCount,sheetcount,i,j,k:integer;
begin
//Provider=Microsoft.Jet.OLEDB.4.0;Data Source=C:\Documents and Settings\Administrator\桌面\6月份外加工费用统计表.xls;Extended Properties=Excel 8.0;Persist Security Info=False

if (Edit1.Text='') then
begin
  MessageDlg('输入的内容为空',mtwarning,[mbOK],0);
  exit;
end;
if OpenDialog1.Execute then
  fname:=OpenDialog1.FileName
else exit;

ExcelToSQL:=ImportExcel.Create(fname);
//ExcelToSQL.Resume;
//ExcelToSQL.OnTerminate:=ThreadDone;


end;

procedure TMain.FormCreate(Sender: TObject);
begin
  ADOQuery1.Active:=True;
end;



procedure TMain.Button3Click(Sender: TObject);
begin
 ADOQuery1.Requery();
end;

procedure TMain.Edit1KeyPress(Sender: TObject; var Key: Char);
begin
if not (key in ['0'..'9',#8]) then key:=#0;
end;

procedure TMain.Button2Click(Sender: TObject);
begin
  with TForm1.Create(self) do
  Show;
end;

procedure TMain.ThreadDone(Sender:TObject);
begin
// showmessage('success');
end;

end.

unit Unit2;

interface

uses
  Classes,ADODB,comobj,excel2000,oleserver,SysUtils;

type
  ImportExcel = class(TThread)
  private
  Fullfilename:string;
  ADOQuery1:TADOQuery;
  k:integer;
  procedure GetEditText;
  { Private declarations }
  protected
  procedure Execute; override;
  public
  Constructor Create(filename:string);
  end;

implementation

uses UMain,dialogs;

{ Important: Methods and properties of objects in visual components can only be
  used in a method called using Synchronize, for example,

  Synchronize(UpdateCaption);

  and UpdateCaption could look like,

  procedure ImportExcel.UpdateCaption;
  begin
  Form1.Caption := 'Updated in a thread';
  end; }

{ ImportExcel }

Constructor ImportExcel.Create(filename:string);
begin
  Fullfilename:=filename;
  Inherited Create(False);

end;

procedure ImportExcel.GetEditText;
begin
  k:=StrToInt(Main.Edit1.text);
end;

procedure ImportExcel.Execute;
var
  excelid:variant;
  i:integer;
begin
  { Place thread code here }
excelid:=Createoleobject('Excel.Application'); //1、创建连接
excelid.visible:=false;
excelid.workbooks.open(Fullfilename); //2、指定文件
Synchronize(GetEditText);

Try
 try
  ADOQuery1:=TADOQuery.Create(nil);
  with ADOQuery1 do
  begin
  ConnectionString:='Provider=MSDASQL.1;Persist Security Info=True;User ID=wu;Data Source=mjgl';
  Close;
  SQL.Clear;
  SQL.Text:='select * from jgfy';
  Open;
  end;
for i:=3 to 1000 do //最大行数1000
begin
  //判断是否结束
  if Trim(Excelid.WorkBooks[1].Worksheets[k].Cells[i,1].Value)<>'' then
  begin
  with ADOQuery1 do
  begin
  Append;
  FieldByName('rdate').Value:=Excelid.WorkBooks[1].Worksheets[k].Cells[i,1].Value;
  FieldByName('moldid').Value:=Excelid.WorkBooks[1].Worksheets[k].Cells[i,2].Value;
  FieldByName('gz').Value:= Excelid.WorkBooks[1].Worksheets[k].Cells[i,3].Value;
  FieldByName('amount').Value:= Excelid.WorkBooks[1].Worksheets[k].Cells[i,4].Value;
  FieldByName('fkfs').Value:= Excelid.WorkBooks[1].Worksheets[k].Cells[i,5].Value;
  FieldByName('maker').Value:= Excelid.WorkBooks[1].Worksheets[k].Cells[i,6].Value;
  FieldByName('jgs').Value:= Excelid.WorkBooks[1].Worksheets[k].Cells[i,7].Value;
  FieldByName('memo').Value:= Excelid.WorkBooks[1].Worksheets[k].Cells[i,8].Value;
  Post;
  end;
  end
  else break;
end; //for
except
  adoquery1.Free;
  excelid.quit;
  showmessage('导入出错!');
end;
finally
  excelid.quit;
  ADOQuery1.Free;
  showmessage('导入成功');
end;
end;

end.

[解决办法]
你在线程中 ShowMessage, 线程怎么可能运行结束？在线程代码中不要带对话框之类的操作，这是忠告！
[解决办法]
用sendmessage