I have an iDVR-E4. I can access the cameras via http://www.idvrviewer.com after entering address, port, password, etc. Works from my droid and also from a laptop, even from my desktop on the internal network.
When I try (internal network) to connect to the dvr in a browser, it displays the login screen, and then a blank page with a link "Web Server". When I click on that nothing happens. I have tried several different computers, and both IE8 and google Chrome browsers.