I have 4 computers on my home network, 3 of which are running Windows 7 pro, and the other one is Windows Vista home. All of the computers are in the same workgroup (I tried using homegroup as well, but it worked terribly and I disabled it), all of them have the same network settings (file and printer sharing: on, network discovery: on, etc), all of them have access to the internet, and for the purposes of troubleshooting, I have disable all AV software and firewalls. For months I was able to connect to all of my computers from any other computer. Suddenly, my main office computer (Windows 7, which I'm also using as a Quickbooks file server, so I NEED it to work!) started losing it's connection and file sharing with the others. I would restart it, and that would fix the problem for anywhere from 1 minute, to 1 week. Now, I simply cannot connect to it at all, with any computers, and rebooting doesn't help. The problem-computer is usually visible in the network window of the other computers, but trying to access it returns an error of 0x80070035 (cannot access, check the spelling, blah blah). If I run Windows Network Diagnostics, it says my computer is configured correctly, but the other computer is the problem. If i run the diagnostics on the problem-computer, it says THE SAME THING. So frustrating! I recently learned that if I type the local IP address of one of my computers into the explorer bar of the problem-computer, BOOM. Instant access. However, If I type the IP address of the problem-computer into any of the others, I get nothing at all... Not even an error. Just... nothing. This has been an EXTREMELY frustrating problem for me for the last few months, and it is very much inhibiting my ability to run my home office. I would really appreciate any help or suggestions. Let me know if you need me to post diagnostic reports or anything. Thanks everyone!