How can I enable or disable the user's ability to change file associations?

A. You can configure a user's computer to enable or disable the ability to change file associations by performing the following steps:

1. Start a registry editor (e.g., regedit.exe).
2. Navigate to the HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\policies\Explorer registry subkey to configure the computer for all users or navigate to the HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Policies registry subkey to configure the computer for the current user. If either subkey doesn't exist, open the Edit menu and select New, Key to create it.
3. From the Edit menu, select New, DWORD Value.
4. Enter the name NoFileAssociate.
5. Set the value to 1 to disable the user's ability to change file associations (this setting doesn't affect Power Users and Administrators); a value of 0 or a missing value enables the user's ability to change file associations.
6. Click OK.
7. Close the registry editor.
8. Restart the computer for the changes to take effect.