I have 1 desktop (hardwired) and 2 laptop (wireless) on a home network. The desktop is XP SP2 X86 and one laptop is the same and the other is Vista. I have a D-Link DI-524 router. All computers see each other find. I can ping with IP or name all computers from each location. The desktop can access each laptop with no problems. Neither laptop can access the desktop even thou they can see it. On the XP laptop I get A " \\Office (desktop) is not accessible" error and on the Vista laptop I get a "Check spelling" error. No firewalls on any computer. Have checked services and all are OK. I'm about to pull my hair out on this one.

If you've checked for firewall software, and not for the windows firewall, make sure you check that too.

If a computer is not accessible, you may have to turn file sharing on. You can do this easily in windows XP by right click a folder you want to share, and clicking properties. There should be a tab dedicated to sharing the folder.

You also need to make sure that the 'Server' service is enabled, and running. You can go to start > run > services.msc, and scroll down until you see it. Make sure it says 'Started' and the startup type is automatic.

I have not only turn off software firewalls but uninstalled them. Sharing is turned on. And as I stated in my original post I checked services and all need services are on and automatic.

Try to access the desktop by IP address, instead of name. You can replace the computer name in the UNC path with the IP and it works the same way.

For example, on my home network with my linux server, I usually use \\192.168.1.50\ instead of \\centos\

Nope luck, still same error messages.

I'm wondering could there be a problem using the router as my DHCP.

Have you tried statically assigning IP addresses to your devices and turning off your DHCP function in your router?

DHCP shouldn't have any effect on the ability of the computers to share files, as long as you can ping between the three PCs just fine. The only thing I can really think of is firewall, but you already turned those off...

This isn't really going to be TOO valuable, but it will tell you if its actually a problem with the permissions, or just with getting a connection to the desktop in the first place, before you authenticate.

Open up command prompt on one of the laptops. Type Telnet <ip of desktop> 139

If, after a few second, the command prompt window blanks out, that means you've successfully connected to the netbios TCP port of the desktop. If not, we know there is something blocking the connection itself, and permissions on the folders haven't even come into play yet.

If you can't get a connection from the laptops, try it on the desktop itself (be sure to use the network IP instead of 127.0.0.1). If you get a connection there, but not from the laptop, there's still some sort of firewall in place blocking the port. If not, the file and printer sharing isn't set up correctly.

OK, I can telnet from the laptops to the desktop. So I am connecting. Must be a problem with the permissions?

Right, that means you're accessing the netbios port on the desktop. So we've ruled out TCP/IP as the problem, NetBIOS is working correctly, a firewall isn't the problem, and everything has connectivity to where it should be.

Next I would check Computer Management from Control Panel > Administrative tools on the desktop. One of the options will be 'Shares' or 'Shared Folders', and you should see your folder listed in there. If not, either the share isn't set up correctly, in which case I would unshare it, and try to share it again, or there is a problem with the network services (Which we've already checked, so that should be fine)

If you see your share in there, I would try connecting to it from the laptop (I'd try it by IP just to eliminate the name as a possible error), in the form of \\DESKTOP_IP\Sharename\ from one of the laptops. As soon as you do that, check "Sessions" in computer management right by Shares. You should see the laptop connecting to the desktop in there.

If those two checks go according to plan, I'd check the actual share permissions themselves. I'll assume you're set up in a workgroup as opposed to a domain. The SHARE permissions on the folder must be set to at least read, for the account that you're using to access the desktop (Or, you can use the Everyone group, to grant permissions, if you trust everyone that has access to your network).
Once the share permissions are set up, if you're sharing the folder from an NTFS drive, you also seed to set the Security tab permissions. When a folder is accessed, the share AND NTFS permissions are compared separately, so if a user or group isn't listed on BOTH tabs, and they're trying to access the files, they won't be able to get through.

I have the Shared Folder and tried with only limited success. Only 1 folder I saw in the Sessions file and it only connected for .03 seconds. I am using NTFS and don't remember setting the Security tab permissions. I'll see what I can do.

If you don't see the security tab, and it's on an NTFS formatted drive, you'll need to go to Control Panel > Folder Options > View Tab > uncheck Use Simple File Sharing at the bottom.

Well I finally solved my networking problem. The error was in the registry. The path was "HKEY-LOCAL-MACHINE\SYSTEM\CurrentControlSet\Control\Lsa". The file changed was "restrictanonymous", set Value data to 0. I would like to thank those who offered help. Hope this helps someone else.