问问：下面的程序有问题吗？我运行就是通过不了，说什么Access Violation问题哦？我也不知道这里的问题到底出现在哪里，因为用了两个类，我想用record，但是说出错，但是用了两个class，程序过程中没有出错，只是运行的时候出了问题，能帮帮我吗？
unit Unit1;

interface

uses
  Windows, Messages, SysUtils, Variants, Classes, Graphics, Controls, Forms,
  Dialogs, ExtCtrls, StdCtrls, jpeg;

/////////******************************
type
  TCarMove=class    //record 
    TTimerXUp:TTimer;
    TTimerXDown:TTimer;
    TTimerYUp:TTimer;
    TTimerYDown:TTimer;
  private
    //{ Private declarations}
  public
    //{ Public declarations}
    procedure TTimerXUpTimer(x,y:integer);
    procedure TTimerXDownTimer(x,y:integer);
    procedure TTimerYUpTimer(x,y:integer);
    procedure TTimerYDownTimer(x,y:integer);
  //public
  end;
///////////////***************
type
  TForm1 = class(TForm)
    Image1: TImage;
    Image2: TImage;
    Button1: TButton;
    PaintBox1: TPaintBox;
    procedure FormCreate(Sender: TObject);
    procedure Button1Click(Sender: TObject);
  private
    { Private declarations }
  public
    { Public declarations }
  end;

var
  Form1: TForm1;
  FCarMove:TCarMove;
  xu,xd,yu,yd:integer;
  a:integer;
implementation

{$R *.dfm}

////////////////////////////////////////*********************
//我想把这些都写成函数，可是中间出了点差错哦
procedure TCarMove.TTimerXUpTimer(x,y:integer);   // 往X正轴运动
var
  TemBit:TBitMap;
begin
  Form1.Repaint;
  TemBit:=TBitMap.Create;
  try
    TemBit.Assign(Form1.Image2.Picture.Graphic);
    Form1.PaintBox1.Canvas.Draw(x-Form1.Image2.Picture.Bitmap.Width,y-Form1.Image2.Picture.Bitmap.Height div 2,Form1.Image2.Picture.Bitmap);  
    x:=x+5;
    //TTimerXUp.Enabled:=False;
    TTimerXDown.Enabled:=False;
    TTimerYUp.Enabled:=False;
    TTimerYDown.Enabled:=False;
  finally
    TemBit.Free;
  end;
  Form1.Image2.Visible:=False;
  xu:=x;//记下X1，之后需要的
end;
procedure TCarMove.TTimerXDownTimer(x,y:integer);
var
  TemBit:TBitMap;
begin
  Form1.Repaint;
  TemBit:=TBitMap.Create;
  try
    TemBit.Assign(Form1.Image2.Picture.Graphic);
    Form1.PaintBox1.Canvas.Draw(x,y-Form1.Image2.Picture.Bitmap.Height div 2,Form1.Image2.Picture.Bitmap);  
    x:=x-5;
    TTimerXUp.Enabled:=False;
    //TTimerXDown.Enabled:=False;
    TTimerYUp.Enabled:=False;
    TTimerYDown.Enabled:=False;
   finally
    TemBit.Free;
  end;
  Form1.Image2.Visible:=False;
  xd:=x;//
end;
procedure TCarMove.TTimerYUpTimer(x,y:integer);
var
  TemBit:TBitMap;
begin
  Form1.Repaint;
  TemBit:=TBitMap.Create;
  try
    TemBit.Assign(Form1.Image2.Picture.Graphic);
    Form1.PaintBox1.Canvas.Draw(x-Form1.Image2.Picture.Bitmap.Width div 2,y-Form1.Image2.Picture.Bitmap.Height,Form1.Image2.Picture.Bitmap);//CarMoveYUp事件过程
    y:=y+5;
    TTimerXUp.Enabled:=False;
    TTimerXDown.Enabled:=False;
    //TTimerYUp.Enabled:=False;
    TTimerYDown.Enabled:=False;
   finally
    TemBit.Free;
  end;
  Form1.Image2.Visible:=False;
  yu:=y;
end;
procedure TCarMove.TTimerYDownTimer(x,y:integer);
var
  TemBit:TBitMap;
begin
  Form1.Repaint;
  TemBit:=TBitMap.Create;
  try
    TemBit.Assign(Form1.Image2.Picture.Graphic);
    Form1.PaintBox1.Canvas.Draw(x-Form1.Image2.Picture.Bitmap.Width div 2,y,Form1.Image2.Picture.Bitmap);
    y:=y-5;
    TTimerXUp.Enabled:=False;
    TTimerXDown.Enabled:=False;
    TTimerYUp.Enabled:=False;
    //TTimerYDown.Enabled:=False;
  finally
    TemBit.Free;
  end;
  Form1.Image2.Visible:=False;
  yd:=y;
end;
/////////////////////////////////////******************************************************************

procedure TForm1.FormCreate(Sender: TObject);
begin
  PaintBox1.Left:=Image1.Left;
  PaintBox1.Top:=Image1.Top;
  PaintBox1.Width:=Image1.Width;
  PaintBox1.Height:=Image1.Height;
  FCarMove:=TCarMove.Create;
  FCarMove.TTimerXUp.Enabled:=False;
  FCarMove.TTimerXUp.Interval:=100;
  FCarMove.TTimerXDown.Enabled:=False;
  FCarMove.TTimerXDown.Interval:=100;
  FCarMove.TTimerYUp.Enabled:=False;
  FCarMove.TTimerYUp.Interval:=100;
  FCarMove.TTimerYDown.Enabled:=False;
  FCarMove.TTimerYDown.Interval:=100;
end;

procedure TForm1.Button1Click(Sender: TObject);
begin
  FCarMove.TTimerYUpTimer(152+7,a);
  a:=a+5;
end;

end.