When you try to import the registry using Registry Editor (Regedit.exe) in real mode, you may receive either of the following error messages:

•	Unable to open registry (14) - System.dat
•	Error accessing the registry: The file may not be complete.

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The real-mode stub of Regedit.exe has the ability to export, import, and create registry files. Regedit.exe uses the internal real-mode registry library to accomplish these tasks. The real-mode code in this library has certain problems with large registry files.

For example, if there are many applications installed, HKEY_CLASSES_ROOT may be quite large. If one of the structures in the System.dat file takes up too much space in conventional memory, the registry cannot be accessed.

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WARNING: Using Registry Editor incorrectly can cause serious problems that may require you to reinstall your operating system. Microsoft cannot guarantee that problems resulting from the incorrect use of Registry Editor can be solved. Use Registry Editor at your own risk.

For information about how to edit the registry, view the "Changing Keys And Values" Help topic in Registry Editor (Regedit.exe) or the "Add and Delete Information in the Registry" and "Edit Registry Data" Help topics in Regedt32.exe. Note that you should back up the registry before you edit it.

To work around this problem, use Registry Editor in protected mode.

For information about how to import the registry, view the "Importing the Registry" Help topic in Registry Editor (Regedit.exe).

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Microsoft has confirmed this to be a problem in Microsoft Windows 95. We are researching this problem and will post new information here in the Microsoft Knowledge Base as it becomes available.

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