I am experiencing a problem with Windows 7 professional, 32 bit, where I am getting an error message (detailed below) when trying to open a file with an unregistered extension. For example, if I rename a file that ends in .txt and contains text, to something with a .test extension the "Open with..." dialog never appears, and I instead get the permission denied message. AVG premium is installed, however through a combination of disabling AVG as well as providing exceptions to the file extension, I can fairly safely rule out intervention from AVG. Windows Defender is disabled, Windows UAC is disabled as well. The Windows Firewall is on, but checking the settings for the firewall suggest no issues would be coming from there.
To add to the fire, if I register the .test extension to open with notepad, the file will open fine and text is displayed as expected. Also of note, I can read the file from command prompt even when the extension is not registered to an application. Using type file.test
I can see the contents of the file