While launching a MFC application(.exe) as OLE server, some time CWinApp::OnFileNew() gets failed; due to this frame window cannot be created and handle to the main window (m_pMainWnd) becomes NULL and error message "Error occurs in mfc42.dll" appeared.
At windows XP, CWinApp::OnFileNew() failed in 1 out of 100 times.
We have not implemented the OnFileNew() in our application; we are using default implementation of OnFileNew().
As per MSDN CWinApp::OnFileNew implements this command differently depending on the number of document templates in the application. If there is only one CDocTemplate, CWinApp::OnFileNew will create a new document of that type, as well as the proper frame and view class.
Problem occurs only at one system and frequency is one out of 100 and error message "Error occurs in mfc42.dll" appeared.
From your information it is rather impossible to guess what is wrong. But I will give you some notes that may help you to find the problem or enhance your question:
"Error occurs in mfc42.dll" seems to be an application specific error message (googling the exact term gives only a few results). So you should be able to locate the executed source sections before the error occurs.
Even when using the default implementation of OnFileNew(), virtual functions of your document class are involved. In this case I would especially check OnNewDocument(). When this returns FALSE, creation of the document and frame window will be stopped (see the MFC sources for CSingleDocTemplate::OpenDocumentFile()).