Quickbooks says "Not Responding" or there are multiple server busy errors occurring after June 11, 2012 or in a new install of QuickBooks Desktop in Windows 7 and Windows 8.
On June 12th, IPv6 became the dominant internet protocol over lpv4. QuickBooks Desktop uses IPv4 to ping and look up names on a network. When pinging the local host, a response of get :::1, indicates your system is using IPv6. If you get 127.0.0.1, it is using IPv4 - this is the desired response.
The following solution will make changes to your Windows operating system. Please consult an IT professional if you have any concerns with performing these steps on your own, or have any questions regarding compatibility with other third party software.
Solution: Use Microsoft "Fix it" tool to configure your computer to prefer IPv4, instead of IPv6