Windows 7 Beta-based and Windows Server 2008 R2-based computers cannot join domains with names longer than 15 characters, according to a Microsoft advisory page. A hotfix for the issue is available for download from the linked page.

The following error message occurs when there are more than 15 characters before the dot in a Domain Name System (DNS) domain name:
The attempt to join this computer to the .com domain failed. The parameter is incorrect. According to Microsoft:
"Consider the following sample domain names:

• Northwindtraders.com has 16 characters before the dot. Therefore, this domain name return the error message.
• Contoso.com has 7 characters before the dot. Therefore, this domain name does not return an error message.
• Fabrikam.treyresearch.litwareinc.com has 8 characters before the dot. Therefore, this domain name does not return an error message."

The upcoming Windows 7 has received predominantly favorable reviews, based on the recently unveiled beta version. Windows Server 2008 R2 is a second release of Microsoft's latest line of server software, and shares its code base with Windows 7.