Does the SHELLEXECUTEINFO's lpparameters cannot too long on windows xp?

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C++

platform

UpdateData(TRUE);

SHELLEXECUTEINFOA sei;
memset(&sei, 0, sizeof SHELLEXECUTEINFOA);
sei.cbSize = sizeof SHELLEXECUTEINFOA;
sei.fMask = SEE_MASK_NOCLOSEPROCESS /*| SEE_MASK_FLAG_NO_UI*/;
sei.lpVerb = "runas";
sei.lpDirectory = GetModulePath();
sei.lpFile = "curl.exe";
sei.lpParameters = m_strCmd;
//MessageBox(m_strCmd, _T("tip"), MB_OK);
sei.nShow = SW_SHOW;
if (!ShellExecuteExA(&sei))
{
    CString strLog;
    strLog.Format(_T("启动curl失败（code:0x%x）"), GetLastError());
    MessageBox(strLog);
    return;
}

In this code,lpParameters is a long string which length over 2048,errors occured when codes run to the"ShellExecuteExA(&sei)",the error is "Unhandled exception in RunCurl.exe(KERNELE32.DLL):0xC0000005:Access Violation."(RunCurl.exe is my project's name).It seems a memory access,but i dont know what makes this.If I reduce the lenth of lpParameters then this function works normal.If I run this function with a long lpParameters(length over 2048) in CMD then it works normal too.And this error never occured on WIN7,I guess if the SHELLEXECUTEINFOA cannot receive a too long string on XP?

What I have tried:

read msdn,debug in xp and WIN7,google