Permission to Use Network Resources
Awhile back, my ability to share files on a local network ceased... from my Windows XP Home desktop computer. When I try to "View Workgroup Computers" inside "My Network Places", the I get the error message: "\\xxxxx is not accessible. You might not have permission to use this network resource. Contact the administrator of this server to find out if you have access permission" where xxxxx is the name of my local workgroup.
The other computers on the network share files just fine including my laptop computer. A search of the phrase "permission to use network resources" turns up lots of comments about the problem but few solutions. Microsoft's Knowledge Base has one article instructing a change in the registry, but that bit was already off on my offending machine. Another KB article suggests starting the computer browser service. It was already running. The article also suggests running Netbios over TCP/IP. I already was.
I've also set a trusted range of IP addresses in Zone Alarm's firewall on each machine. I have file sharing turned on, and the workgroup name is the same on all machines. I even tried David Lawrence's suggestion of naming the user on two machines the same.
Maybe those articles will help you, but the search for my solution continues...