Calling convention error on COM call

I get "Run-Time Check Failure #0 - The value of ESP was not properly
saved across a function call."
when I call the method of the COM object. This problem happens only on
certain machines, not all.
In-proc server is FTM and client is STA. I suspect marshalling setting
and object creation. I have given details below, please let me know,
if catch anything wrong. This method just passes ENUM value. I am not
using custom proxy.

Client
-------------
CoInitializeEx(0,COINIT_APARTMENTTHREADED);

enum A valA = I_D;
ITest* pTest = 0;
CoCreateInstance();
pTest->SetMode(I_D); //Run-Time Check Failure #0 - The value of ESP
was not properly save

Server TestDLL.dll
--------------------------
0) Registry shows

[HKEY_CLASSES_ROOT\Interface\{F8D85DAA-098B-4947-8B08-E253A1D7499D}]
@="ITest"

[HKEY_CLASSES_ROOT\Interface\{F8D85DAA-098B-4947-8B08-E253A1D7499D}
\ProxyStubClsid]
@="{00020424-0000-0000-C000-000000000046}"

[HKEY_CLASSES_ROOT\Interface\{F8D85DAA-098B-4947-8B08-E253A1D7499D}
\ProxyStubClsid32]
@="{00020424-0000-0000-C000-000000000046}"

[HKEY_CLASSES_ROOT\Interface\{F8D85DAA-098B-4947-8B08-E253A1D7499D}
\TypeLib]
@="{315BE7EE-B39B-41F7-9B2A-9CF2824E6F27}"

1) _MERGE_PROXY preprocessor has been removed.

2) C++/H
STDMETHOD(SetMode)(enum A iMode );
STDMETHODIMP CTest::SetMode(enum A iMode)
{
    m_A = iMode;
    return 0;
}

3) IDL
enum A
{
   I_A = -1,
   I_B = 1,
   I_C = 2,
   I_D = 3
};

[
    object,
    uuid(F8D85DAA-098B-4947-8B08-E253A1D7499D),
    dual,
    nonextensible,
    helpstring(""),
    pointer_default(unique)
]
interface ITest : IDispatch
{
    [id(3), helpstring("")] HRESULT SetMode(enum A iMode);
};

[
    uuid(315BE7EE-B39B-41F7-9B2A-9CF2824E6F27),
    version(1.0),
    helpstring("Type Library")
]
library CTestLib
{
    importlib("stdole2.tlb");
    [
        uuid(8B2E3F9E-AA9E-4579-BBC3-4B272DEF2520),
    ]
    coclass CTest
    {
        [default] interface ITest;
    };

};

RGS
-----
HKCR
{
    TestDLL.CTest.1 = s 'CTest Class'
    {
        CLSID = s '{8B2E3F9E-AA9E-4579-BBC3-4B272DEF2520}'
    }
    TestDLL.CTest = s 'CTest Class'
    {
        CLSID = s '{8B2E3F9E-AA9E-4579-BBC3-4B272DEF2520}'
        CurVer = s 'TestDLL.CTest.1'
    }
    NoRemove CLSID
    {
        ForceRemove {8B2E3F9E-AA9E-4579-BBC3-4B272DEF2520} = s 'CTest Class'
        {
            ProgID = s 'TestDLL.CTest.1'
            VersionIndependentProgID = s 'TestDLL.CTest'
            ForceRemove 'Programmable'
            InprocServer32 = s '%MODULE%'
            {
                val ThreadingModel = s 'Free'
            }
            'TypeLib' = s '{315BE7EE-B39B-41F7-9B2A-9CF2824E6F27}'
        }
    }
}

HKCR
{
    NoRemove AppID
    {
        '%APPID%' = s 'TestDLL'
        'TestDLL.DLL'
        {
            val AppID = s '%APPID%'
        }
    }
}

Thanks
Ramesh