I also have a HS-DH500GL that was working well for about a year and then just quit. The NasNavi utility can't find it (same result as if the drive was powered off). I uninstalled NasNavi and re-ran the CD to configure the drive and install software. The installer appears to work, but reports failure when it runs the re-installed NasNavi. Can't access the config webpage (web browser reports page not found).
The only thing that works is ping. I disconnected everything from the router except the computer , the HS-DH500GL, and the cable-modem. Ping works. DIsconnecting the HS-DH500GL causes ping to fail, so nothing else is responding at that address. I have no idea how to turn off all the firewall crap that comes with WinVista, so I swapped computers in this setup. This computer runs Linux without firewall software. Same results running ping. Also, no config webpage.
I see several have had similar trouble and no good answers, so I'm probably on my own solving this problem. To recover the data in the HS-DH500GL, I connected the harddrive in the HS-DH500GL directly to a computer. I recovered my data. I don't really care if the HS-DH500GL runs again because I won't trust it.
If anyone else wants to try this, here's what you need.
1. a desktop computer with a motherboard that can use SATA harddrives, and SATA cables for power and data.
2. a USB drive to transfer the data to
3. a Linux CD. Any 'live' cd distro should work ok. I used Linux Mint 8 (gnome).
info -- http://www.linuxmint.com
CD .iso download -- http://ftp.heanet.ie/pub/linuxmint.com/stable/8/LinuxMint-8.iso
Linux expertise is not necessary. If you can run Windows Explorer you can probably do this.
The 'live' CD runs directly from the CD in ram. No need to install. Run the CD to check that it works with your computer, monitor, etc.
Disconnect the power cord and open the desktop computer case to check for SATA cables. Ideally, the computer has a SATA harddrive. Just disconnect HS-DH500GL. Otherwise, find a SATA power cable and a SATA data cable, and find a SATA connector on the motherboard. Disconnect all to the harddrive data cables the motherboard.
Disconnect the power cord and open the HS-DH500GL. To remove the front panel, take out the screw between the rubber feet. There is a circuit board with LEDs retained by two screws. Remove the screws and carefully pull the board out. There's a card-edge connector two SATA connectors on this board so there's a bit of friction to overcome.
Connect the desktop SATA cables to the harddrive inside the HS-DH500GL. The desktop computer powers the HS-DH500GL harddrive, so don't connect anything else to the HS-DH500GL.
Power the desktop computer and boot the Linux CD. With Linux Mint, there is a 'Computer' desktop icon that will show the drives. Each partition appears separately. There several partitions on the HS-DH500GL harddrive. Take your best guess which one, click on it and select 'mount'. The mounted partition appears as a new desktop icon. Open it and see if you guessed right. Repeat until you find your data
Plug in a USB drive. This should appear as a new item in 'Computer' , or it may auto-mount. Open the USB drive. Create a folder and copy/paste or drag/drop the files from HS-DH500GL to the USB drive.
When it's done, poke the desktop computer's power button and select 'shutdown'.