This problem occurs when you open the Edit File Type dialog box for the Drive or File Folder registered file types. For example, this problem occurs for folders if you complete the following procedure:
1. Open the folder, and then click Folder Options on the Tools menu.
2. Click File Folder in the Register file types list, and then click Advanced.
3. After you perform this procedure, the None setting is removed from the value data for the Default string value in the following registry key:
NOTE: This problem occurs even if you do not create a new action, edit existing actions, or change the default action in the Edit File Type dialog box.
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