DeadLock in directShow, mutlti video resizing - c++

Question

1，I'd like to show 9 videos at same time.
2，I have a main thread which create all the windows and handle the WM_* message, also in charge of: A), init vmrvideorender9, MediaControl B), connect filter C), stop and release the MediaControl. and other things.
3，For every video, there is also a render thread which is for sample delivering.
Now, I have many deadlock, they hang at different place and CPU is very high.
The deadlock most happens when resizing the windows.
for example: when I call the following function, sometimes it can consume 40 seconds and sometimes it just hang inside the function.
Void GetVMR9VideoRender()
{
hr = CoCreateInstance(CLSID_VideoMixingRenderer9, NULL, CLSCTX_INPROC,
IID_IBaseFilter, (LPVOID *)&pRender.p);
if (FAILED(hr))
{
return NULL;
}
CComPtr <IVMRFilterConfig9> pConfig;
hr =pRender->QueryInterface(IID_IVMRFilterConfig9, (void**)&pConfig);
if (FAILED(hr))
return NULL;
pConfig->SetRenderingMode(VMRMode_Windowless);
pConfig->SetNumberOfStreams(1);
CComPtr<IVMRWindowlessControl9> lpDefWC;
hr = pRender->QueryInterface(IID_IVMRWindowlessControl9, (LPVOID*)&lpDefWC.p);
if (FAILED(hr))
{
return NULL;
}
m_lpDefWC = (IVMRWindowlessControl*)lpDefWC.p ;
CComPtr<IVMRAspectRatioControl9> lpARC;
hr = pRender->QueryInterface(IID_IVMRWindowlessControl9, (LPVOID*)&lpARC.p);
if (FAILED(hr))
{
return NULL;
}
m_lpARC = (IVMRAspectRatioControl*)lpARC.p ;
return pRender;
}