I had the same problem, along with several basic installation problems, and spent hours with tech support, and couldn't solve the problem. I took the automatic protection mode off in IE security settings and after a reboot, everything worked.
I also installed a third camera, and came to the conclusion that the other two had to be unplugged during the installation of the third...I believe that having one plugged in while trying to install a second, causes problems...just my belief..I now have two 930's and one 932, and all work perfectly...
ALSO, if you do not want to change security settings, try FIREFOX. Camera work perfectly without reducing security.
Hope this works...it took me two weeks to get these working...one of my last steps included installing a new DIR-655 router, and first updating the firmware before installing the cameras!!
PS: After the new router and security changes, and unplugging the first camera, the second took about 2 minutes to install; then immediately unplugging the second camera, the third took about 2 minutes to install....couldn't have been faster!