Are you getting this by just entering the IP address? This error is usually a permissions error - connecting to a specific .htm page.
If you are just entering http://192.168.0.100 for example and getting this error something is definitely wrong. if you are entering something like 192.168.0.100/Home.htm, then yes sometimes you may get that error if you are not considered logged in.
D-Link US does not sell this camera so I am not sure about specific errors or issues. Hopefully another user or the tech from Canada who is helping you can find out.