This article was previously published under Q296248
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This article was written about products for which Microsoft no longer offers support. Therefore, this article is offered "as is" and will no longer be updated.
When you attempt to install Snapshot viewer 9.0, you receive the following error message:
MFC42.dll file is in use
This behavior occurs when a program attempts to modify the Mfc42.dll file . It can occur with any program written in Visual C++ that uses the Microsoft Foundation Class Library 4.2.
To work around this issue, install Snapshot viewer 8.0 (Snpvw80.exe). You have to first quit all programs that may be using MFC42.dll. To do so, use one of the following methods listed.
NOTE: This method applies only to computers running Microsoft Windows NT or Microsoft Windows 2000.
Press CTRL+ALT+DELETE, and then click Task Manager.
Click the Processes tab.
For every item on the list, select the item and then click End Task. This will terminate all programs that use MFC42.dll.NOTE: System-critical processes will not be terminated.
Close the Task Manager, and then install the Snapshot viewer.
Restart your computer in MS-DOS mode.
Open the directory where MFC42.dll is located, and then rename the file MFC42.old.
Restart the computer and install the Snapshot viewer.NOTE: This method prevents you from using any program that requires MFC42.dll until the file is replaced when you install the Snapshot viewer.
Mfc42.dll (Microsoft Foundation Class Library 4.2) is a run-time file that is used by all programs written in Visual C++ currently running on your computer. While a program that uses this file is active, no other program can overwrite this file.