奇怪的问题：是什么影响了获取窗口标题？

[TurtleRock]

我的程序是一个控制台程序，其中有枚举窗口函数，运行正常，能枚举窗口并显示窗口标题，
但是我在程序中又加入了一段抓屏的程序和内存流操作后，抓屏正常，而枚举窗口却无法了。
逐步调试发现：程序枚举窗口后，用GetWindowText获取标题，开始都正常，枚举到某一个窗体时，GetWindowsText处出错，而且不提示错误，程序就死在那儿。
一旦把抓屏和内存流操作的代码去掉后，枚举就又会一切正常，两段代码之间应该没有任何关系啊？怎么会这样呢？当不加抓屏时，程序大小197k，加了后493k
百思不得其解，痛苦中，大家帮我分析一下可能的原因？
枚举代码如下(其中WinListStr为全局变量)：
function EnumWindowsProc(hwnd:HWND;lParam:DWORD ):boolean; stdcall;
var
szCaption: array[0..256] of Char;
begin
if GetWindowText(hwnd,szCaption,sizeof(szCaption))<>0 then
if (length(trim(szCaption))>0) and (szCaption<>'Default IME') then
WinListStr:=WinListStr+szCaption+','; //句柄＋名称
result:= TRUE;
end;
Function WinList:String;
begin
WinListStr:='';
EnumWindows(@EnumWindowsProc,0);
Result:=WinListStr;
end;

[TurtleRock]

谢谢两位回帖，这段程序单独运行是绝对没有问题的。
抓屏单独用了一个单元，在程序中只要包含了这个单元，即使未引用其中的函数，枚举窗口过程中程序就会死去，但抓屏运行正常，没有任何问题。两个单独运行都没问题，一旦引用该单元，枚举窗口出问题。
大家再帮我分析一下可能的原因...
unit ScreenManage;

interface

uses
Windows,Classes,Graphics,Forms,ZLib,SysUtils;

type
TScreenInfo = record
DataSize: Integer;
Host: string;
Port: Integer;
Verycolored:Integer;
DrawCur:Boolean;
AutoRefresh:Boolean;
TransStop:Boolean;
ClockMouse:Boolean;
ClockKey:Boolean;
FGX:Integer;
FGY:Integer;
end;
PScreenInfo=^TScreenInfo;

procedure STGetScreenToBmp(ScreenInfo:TScreenInfo;StreamName:TMemoryStream);

procedure STCompareStream(STTFirstStream,STTSecondStream,STTCompareStream:TMemorystream);
procedure STResumeStream(STTFirstStream,STTSecondStream:TMemorystream);
procedure CompressBitmap(bmp:TMemoryStream; Data:TMemoryStream);
procedure UnCompressBitmap(Data:TMemoryStream; bmp: TMemoryStream);

implementation

procedure STGetScreenToBmp(ScreenInfo:TScreenInfo;StreamName:TMemoryStream);
var
STTbmp:Tbitmap;
Cursorx, Cursory: integer;
dc: hdc;
STTcan: Tcanvas;
R: TRect;
DrawPos: TPoint;
STTCursor: TIcon;
hld: hwnd;
Threadld: dword;
mp: tpoint;
pIconInfo: TIconInfo;
begin
STTbmp := Tbitmap.Create; {建立BMPMAP }
STTcan := TCanvas.Create; {屏幕截取}
dc := GetWindowDC(0);
try
STTcan.Handle := dc;
StreamName.Position :=0;
R := Rect(0,0,Screen.Width,Screen.Height
STTbmp.Width := R.Right;
STTbmp.Height := R.Bottom;
STTbmp.Canvas.CopyRect(R, STTcan, R);
STTbmp.SaveToStream(StreamName);
finally
releaseDC(0, DC);
end;
STTcan.Handle := 0;
STTcan.Free;
if ScreenInfo.DrawCur then
begin
GetCursorPos(DrawPos);
STTCursor := TIcon.Create;
getcursorpos(mp);
hld := WindowFromPoint(mp);
Threadld := GetWindowThreadProcessId(hld, nil);
AttachThreadInput(GetCurrentThreadId, Threadld, True);
STTCursor.Handle := Getcursor();
AttachThreadInput(GetCurrentThreadId, threadld, False);
GetIconInfo(STTcursor.Handle, pIconInfo);
cursorx := DrawPos.x - round(pIconInfo.xHotspot);
cursory := DrawPos.y - round(pIconInfo.yHotspot);
STTbmp.Canvas.Draw(cursorx, cursory, STTCursor);
DeleteObject(pIconInfo.hbmColor);
DeleteObject(pIconInfo.hbmMask);
STTcursor.ReleaseHandle;
STTCursor.Free;
end;
case ScreenInfo.Verycolored of
0:STTbmp.PixelFormat:=pf24bit;
1:STTbmp.PixelFormat:=pf8bit;
2:STTbmp.PixelFormat:=pf4bit;
end;
STTbmp.SaveToStream(StreamName);
STTbmp.Free;
end;


procedure STCompareStream(STTFirstStream,STTSecondStream,STTCompareStream:TMemorystream);
var
I: Integer;
P1, P2, P3: ^Char;
begin
STTCompareStream.Clear;
//--------------------------------------------------
P1 := STTFirstStream.Memory;
P2 := STTSecondStream.Memory;
STTCompareStream.SetSize(STTFirstStream.Size);
P3 := STTCompareStream.Memory;

for I := 0 to STTFirstStream.Size - 1 do
begin
if P1^ = P2^ then
P3^ := '0'
else
P3^ := P2^;
Inc(P1);
Inc(P2);
Inc(P3);
end;
//--------------------------------------------------
STTFirstStream.Clear;
STTFirstStream.CopyFrom(STTSecondStream,0);
end;

procedure STResumeStream(STTFirstStream,STTSecondStream:TMemorystream);
var
I: Integer;
P1, P2: ^Char;
begin
//---------------------------------------------
P1 := STTFirstStream.Memory;
P2 := STTSecondStream.Memory;

for I := 0 to STTFirstStream.Size - 1 do
begin
if P2^ = '0' then P2^ := p1^;
Inc(P1);
Inc(P2);
end;
//---------------------------------------------
STTFirstStream.Clear;
STTFirstStream.CopyFrom(STTSecondStream,0);
STTSecondStream.Position:=0;
end;

procedure CompressBitmap(bmp:TMemoryStream; Data:TMemoryStream);
var
cs : TCompressionStream;
ms : TMemoryStream;
begin
try
ms := TMemoryStream.Create;
cs := TCompressionStream.Create(clDefault, ms);
bmp.SaveToStream(cs);
cs.Free;
ms.Position:=0;
Data.LoadFromStream(ms);
Ms.Free;
except
end;
end;

procedure UnCompressBitmap(Data:TMemoryStream; bmp: TMemoryStream);
var
ms : TMemoryStream;
buf : pointer;
size : integer;
TmpStr: String;
begin
SetLength(TmpStr, Data.Size);
Move(Data.Memory^, TmpStr[1], Data.Size);

try
DecompressBuf(@TmpStr[1], Length(TmpStr),Length (TmpStr) * 3, buf, size);
except
end;
ms := TMemoryStream.Create;
ms.Write(buf^, size);
FreeMem(buf);
ms.Position := 0;
Assert(bmp<>nil);
bmp.LoadFromStream(ms);
ms.Free;
end;

end.

[SonicX]

没有回调你也能编译通过???
GetWindowText(hwnd,@szCaption,sizeof(szCaption))

[xixuemao]

这段代码没看出问题，抓屏？

[TurtleRock]

大家提个建议，看看可能是什么原因引起的？