用IP+port不能连接到数据库。查看日志：
server SuperSocket Info:Bind failed on TCP port 1433

NETSTAT -AN 也没有看到侦听1433端口。

CAUSE
Changing the Virtual SQL Server IP address with the Cluster Administrator tool. For a default instance of virtual SQL Server, the following registry value points to a previous IP address: 

HKLM\Software\Microsoft\MSSQLServer\Cluster

For a named instance of virtual SQL Server, the following registry value points to a previous IP address: 

HKLM\Software\Microsoft\Microsoft SQL Server\Instance Name\Cluster\ClusterIpAddr 
    (我的确是在群集管理器里直接更改过SQL群集IP.…………)

RESOLUTION
To resolve the problem, follow the steps 

 section of the article, select Remove and replace an existing IP Address: 

 SQL Server Books Online to resolve the problem.

.
1. Insert the SQL Server 2000 Enterprise Edition CD, and then click SQL Server 2000 Components. 
2. Click Install Database Server. 
3. On the Welcome screen, click Next.
4. Type the name of the virtual server that you want to modify, and then click Next. 
5. Click the Advanced options tab, and then click Next. 
6. Click Maintain a Virtual Server for Failover Clustering, and then click Next. 
7. In the Failover Clustering dialog box, you can: • Add an IP address for additional networks.
• Remove and replace an existing IP address.
• Remove IP addresses that you do not need. 
After you make these changes, click Add, and then click Next.

Note Assign only one IP address for each network and one network for each network adapter. SQL Server requires that each IP address that is assigned to it have its own unique subnet mask. SQL Server does not support multiple IP addresses on the same subnet because this may result in duplicated names on the network. For example, if you have a public network and a private network and you want to assign an additional IP address to your SQL Server virtual server, you must add another network adapter to each node to create a new network. You can then assign the additional IP address to the new network. 
8. Make any changes to the nodes, and then click Next. 
9. Verify the requested user information and password, and then click Next.