Intermittant StgCreateDocfile / StgOpenStorageEx failure

Question

I'm posting this on the hops that someone else has run across this.
Our legacy application uses structured storage.  It's been working well for the last 15 years... (Damn I'm old!)
In that few days we've received reports from customers that they are receiving an error when opening data. The failure occurs when StgOpenStorageEx is called.  it returns HRESULT 0x80004002, with error message "Class does not support automation
or does not support expected interface."
Interestingly enough if I try the StgOpenStorageEx call with IID_IPropertySetStorage instead of IID_IStorage it returns an interface.  
As noted the same code has been running properly for 15 years.  Now we've got several reports of these failures.  All appear to have happened on Windows 7 Pro, 64 bit, with up to date with Windows Update fixes/patches/updates.
I'd sure appreciate notification if any one else has run across this.  It is intermittent.
Thanks for any help.
Here is the code to open the file:
STDMETHODIMP Session::LoadFile(BSTR file)
HRESULT hr;
String f(file);
CComPtr<IStorage> store;
// go and make the file this is to be...
hr = StgOpenStorageEx(f,
 STGM_DIRECT | STGM_READ | STGM_SHARE_DENY_WRITE, 
 STGFMT_ANY, 0, NULL, NULL, 
 IID_IStorage, (void **) &store);
if (hr == S_OK)
try
CComPtr<IStream> stream;
// got a file to write to....
hr = store->OpenStream(OLESTR("Session"), 0, STGM_DIRECT | STGM_READ | STGM_SHARE_EXCLUSIVE, 0, &stream);
if (hr == S_OK)
hr = Load(stream);
// and release the stream
stream.Release();
if (hr == S_OK) mPath = file;
catch(...)
hr = E_FAIL;
// and be done
store.Release();
else
return hr;
To save the file...
STDMETHODIMP Session::SaveFile(BSTR file)
HRESULT hr;
String f(file);
CComPtr<IStorage> store;
// go and make the file this is to be...
    hr = StgCreateDocfile(f,
 STGM_CREATE | STGM_DIRECT | STGM_READWRITE | STGM_SHARE_EXCLUSIVE,
 0,
 &store);
if (hr == S_OK)
try
CComPtr<IStream> stream;
// got a file to write to....
hr = store->CreateStream(OLESTR("Session"),
STGM_CREATE | STGM_WRITE | STGM_DIRECT | STGM_SHARE_EXCLUSIVE,
0, 0, &stream);
if (hr == S_OK)
hr = Save(stream, TRUE);
if (hr == S_OK) mPath = file;
// and release the stream
stream.Release();
catch(...)
hr = E_FAIL;
// and be done
store.Release();
return hr;

Answer 1

If the issue is intermittent and it works when the operation is retried programmatically several times, then consider it a workaround.
Maybe the problem is caused by some antivirus or non good programs and it has sense to investigate some  more configuration patterns of client machines.