Outlook Error Message: "This operation has been cancelled due to restrictions in effect..."

THIS ISSUE IS COMMON AFTER UNINSTALLING GOOGLE CHROME OR MOZILLA FIREFOX.

If you received this error after uninstalling any application that takes over the HTML open command (including, but not limited to, Chrome & Firefox browsers) you may also need to change the HTM/HTML association in the registry.

*It is recommended that you backup your registry before following the steps below:

1. Start, click Run, type Regedit in the Open box, and then click OK.
2. Browse to HKEY_CURRENT_USER\Software\Classes\.html
3. Right click the value for the .html key and select Modify…
4. Change the value from "ChromeHTML" to "htmlfile" (or from FireFoxHTML to htmlfile)