Hi,
Is the computer connected to a workgroup?
There are scenarios when a computer is connected to a workgroup and the name for the specific computer running an operating system isn't the same as that of the other computers. Here's a link for instance:
Refer to the suggestions from Ztruker posted on August 27th, 2009:
You can also try disabling network firewall and Norton security software temporarily, after you enable an Internet firewall, you may not be able to search, or "browse," for other computers on your home or office network, and you may not be able to share files with other computers on oyour home r office network.
Important Note: Security software can help protect your computer against viruse and other security threats. In most cases, you shouldn't disable your antivirus software. If you have to temporarily disable it to install other software, you should re-enable it as soon as you're done. If you're connected to the Internet or a network while your antivirus software is disabled, your computer is vulnerable to attacks.
For issues related to Domain name grayed out, you can refer to the link:
As suggested earlier, you can also post the same query on Microsoft TechNet forum.
Please feel free to ask more queries on Windows.