Cannot see anything except Win7 boxen in Explorer

I have a lot more than those three in there, and all three of those mentioned were checked. I also activated the Netlogon Service (since one of the servers on the LAN will eventually become a Domain Controller, as I play around with and learn Active Directory over the next few months). I also allowed Peer to Peer Collaborations Foundation Properties. Everything saved, system rebooted and...SUCCESS.

I'm not sure what went wrong, but as of now it looks good from pretty well all my machines, including the home theatre box and both VMs.

Thanks to one and all. If anybody has an idea on what might have changed I'd like to make note of this as well. Happy 2012 all (and GO GIANTS <G>)

Unfortunately, that wasn't the problem. Now 4 hours later everything's back the way it was. Once again I ran full scans and found nothnig.

However, something said a while ago looks like it may be an issue. IPv6. When I disable IPv6 I can see everything. It seems that the systems are looking first for an IPv6 connection and not going any further and also looking for IPv4 NICs. What's odd is that I disabled it earlier today and it's back now. What's even odder is that this one machine having IPv6 enabled buggers up the entire network. I've not changed any adapter settings on the other boxen, just this one.

Any thought on how to keep IPv6 support from re-enabling itself, why it IS re-enabling itself in the first place and why only one computer using this protocol is messing up all the other Win7 boxes on the LAN?

If you want to learn to be a professional sysadmin--which is the impression I get from your wanting to setup a domain to learn on--one of the skills you need to cultivate is knowing how to isolate complex issues into simple problems so know where to start when you're confronted with something that doesn't have a ready-made solution listed in the MS KB or on Technet.

Break this one down further to isolate where the problem is. If it was my network, I'd try a few things like this:

Can your XP boxes see each other? Can they see themselves on their own list of networked computers? If not, then the problem is on the XP boxes.

What happens if you connect one XP box and one W7 box using a crossover cable? Do they see each other? If so, then something else on your network is interfering with sharing.

What happens if you set up DHCP, DNS and WINS servers on the network instead of using static addressing?

What happens if you disconnect all computers that are going into IPv6 mode? Does that make the rest of the network work properly?

Troubleshoot why some of your computers are reenabling IPv6 autonomously.

What happens if you get two empty hard drives and swap out your existing HDs from two computers and install fresh copies of XP and W7 on two computers? If you connect the two new installs with a crossover cable, can they see each other? If they don't see each other out of the box, then you have either made a configuration error or the installation images you're using are damaged. What if you connect the two test PCs to your network switch? What if you start installing the software and utilities you usually install on all your systems without thinking about it too much? Do they stop seeing each other after you install a certain program?

If you do all of this, I'm pretty sure you'll be able to isolate the problem down from 'my network doesn't work' to 'my network doesn't work when ________,' and that's something much easier to solve.