OK. Here is what I would do. I would uninstall geovision and re install it. When you uninstall it you must delete everything in remove programs that has to do with geovision. Also delete the 2005 c++ redistributable. After that go to your c drive and delete the geo vision folders. then restart and reinstall. I would go to the geovision website and download version 8.5.9. 8.5.7 is pretty new but in the past whenever this type of thing happens it is because the software is too old so you should get the newest version. It is free you just have to click on the software tab and it will be there.
The usb dongle should automatically install drivers. You shouldn't have to. But don't do it first. wait until everything else is working properly the plug the dongle in and let it do its thing. Then restart.
Also, when you uninstall geovision there will be one thing in the remove programs part that wont go away so just leave it. I think it is geovision mxpg.
After this is all done try adding the cameras.