I have to believe this is some firewall component, nothing else makes much sense here.
I tend to agree with you GRJ, it's possible that one firewall says it's disabled, but really isn't. Add to that the fact that Vista has always had networking issues on *some PCs* and the plot really thickens. My thoughts also wander to the fact that the 321 DID show up once on this PC, but the network path couldn't be found, and then that same PC is no longer BrowseMaster, even when it is forced to be by the addition of "isdomainmaster=true & maintainserverlist=yes". Did that setting change to "false" and "no" when you found that your PC was no longer the BrowseMaster?
Now, just maybe, it has something to do with something I saw but have no expertise in, in the ipconfig query, "Tunnel adapter Local Area Connection* 6 and *7". Would they have the ability to interfere with locating another device? Maybe someone with some knowledge about that could pipe in here and help this poor guy get his 321 working on his own PC.
I know it's not the 321, that's a given since the other PCs can see and map to it, it has to be the Vista PC (laptop?). But short of digging into the bowels of Vista Business, which no human should ever have to do, I'd say there is something seriously amiss with that PC. Especially since you can go in and configure the 321 with either of the other 2 PCs on that network. Either NetBIOS or one of the firewalls has gone A.W.O.L. and joined the dark side! Corrupt file, setting stuck in the registry, etc etc, but all too much to do through a forum.
My gut reaction is to say to reload the Vista PC from scratch and see if that clears up the problem? I know, easy to say, but probably impossible to do, as it is with 2 of my 4 PCs. I have 1 XP PC that got XP the day it was released, I have so much software on it that I'd never find all the discs again. But, it has also never given me a moment of grief, except when 1 of it's RAID 1 drives died. That PC was actually up and running for over 3 years without a reboot! HighMaster2, have I given you enough food for thought to consider dumping Vista and going "forward" to XP yet?
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Just kidding of course, it's only my personal opinion that XP is probably the best O/S Bill G has ever put out, although 7 is showing some serious promise, even though it's built on the Vista codebase!
GRJ, Joe, D-Link, anyone care to comment on my shots in the dark? P.S. As a side note, I have been building custom PCs for people and fixing them, and networks, for over 20 years, and I've never come across something like this before. And it even moreso adds to my thoughts that Vista may replace Windows ME as Bill G's WORST IDEA EVER!!!
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Ryder