Can't see one network device, but can 'see' the rest...totally baffled

So, I have a little file server called the Zyxel NSA320. I had it all set up and working great for about two months.

Now, suddenly, for no apparent reason, it no longer shows up in My Network and I can't map to its shares. All other devices on the LAN show up just fine. Yes, the Zyxel is on the appropriate workgroup, etc.

Here's the bizarre stuff...I can ping its IP, get to it's admin page via browser, the Network window shows the servers' media server (!) and I can 'see' the server just fine on another Vista PC in my house on the same network...but not from mine which is where I need to manage it. I've checked all network and firewall settings I know to check and nothing seems to be out of whack or wrong. I'm truly baffled here. Any help would be greatly appreciated.

Freaking just found it. For some totally unknown reason, the freaking client for microsoft windows was not installed on the network adapter. It somehow disappeared. Reinstalled, rebooted and now the freaking server shows on the network list. Unbelievable.