Well, it's very interesting that you can't login to either of them. If you did reset the device (by holding the reset button for 10 seconds) then lets look at some other things; When you reset the device, the IP address, like you said, is in fact 192.168.0.50. Now, before you type that into the address bar make sure you're connected directly to one of the 4 ports. You also have to set a static IP on your network adaptor to match that of the DAP, so in your adaptor properties set an IP address of 192.168.0.60 and you should be able to login to it.
If you still can't login to it; Ping the device in the command prompt (Ctrl + R - then type cmd). Type 'Ping 192.168.0.50" if you get 4 replies then you should be able to login to it. If you get replies and the configuration page won't come up; Make sure you don't have any proxy settings in the browser or just Reset the browser and try a different one. Or disable any firewalls you may have.
If the ping requests say "Request Timed Out" then go ahead and reset the device again.
Best of Luck,