java.sql.SQLException: [Microsoft][SQLServer JDBC Driver]Error establishing socket.
    at com.microsoft.jdbc.base.BaseExceptions.getException(Unknown Source)
    at com.microsoft.jdbc.base.BaseExceptions.getException(Unknown Source)
    at com.microsoft.jdbc.sqlserver.tds.TDSConnection.<init>(Unknown Source)
    at com.microsoft.jdbc.sqlserver.SQLServerImplConnection.open(Unknown Source)
    at com.microsoft.jdbc.base.BaseConnection.getNewImplConnection(Unknown Source)
    at com.microsoft.jdbc.base.BaseConnection.open(Unknown Source)
    at com.microsoft.jdbc.base.BaseDriver.connect(Unknown Source)
    at java.sql.DriverManager.getConnection(DriverManager.java:582)
    at java.sql.DriverManager.getConnection(DriverManager.java:185)
    at com.lzw.dao.Dao.<clinit>(Dao.java:41)
    at com.lzw.login.Login$2.actionPerformed(Login.java:54)
    at javax.swing.AbstractButton.fireActionPerformed(AbstractButton.java:1995)
    at javax.swing.AbstractButton$Handler.actionPerformed(AbstractButton.java:2318)
    at javax.swing.DefaultButtonModel.fireActionPerformed(DefaultButtonModel.java:387)
    at javax.swing.DefaultButtonModel.setPressed(DefaultButtonModel.java:242)
    at javax.swing.plaf.basic.BasicButtonListener.mouseReleased(BasicButtonListener.java:236)
    at java.(Component.java:6216)
    at javax.swing.JComponent.processMouseEvent(JComponent.java:3265)
    at java.(Component.java:5981)
    at java.awt.Container.processEvent(Container.java:2041)
    at java.(Component.java:4583)
    at java.awt.Container.dispatchEventImpl(Container.java:2099)
    at java.(Component.java:4413)
    at java.awt.LightweightDispatcher.retargetMouseEvent(Container.java:4556)
    at java.awt.LightweightDispatcher.processMouseEvent(Container.java:4220)
    at java.awt.LightweightDispatcher.dispatchEvent(Container.java:4150)
    at java.awt.Container.dispatchEventImpl(Container.java:2085)
    at java.awt.Window.dispatchEventImpl(Window.java:2475)
    at java.(Component.java:4413)
    at java.awt.EventQueue.dispatchEvent(EventQueue.java:599)
    at java.awt.EventDispatchThread.pumpOneEventForFilters(EventDispatchThread.java:269)
    at java.awt.EventDispatchThread.pumpEventsForFilter(EventDispatchThread.java:184)
    at java.awt.EventDispatchThread.pumpEventsForHierarchy(EventDispatchThread.java:174)
    at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:169)
    at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:161)
    at java.awt.EventDispatchThread.run(EventDispatchThread.java:122)
Exception in thread "AWT-EventQueue-0" java.lang.NullPointerException
    at com.lzw.dao.Dao.getUser(Dao.java:120)
    at com.lzw.login.Login$2.actionPerformed(Login.java:54)
    at javax.swing.AbstractButton.fireActionPerformed(AbstractButton.java:1995)
    at javax.swing.AbstractButton$Handler.actionPerformed(AbstractButton.java:2318)
    at javax.swing.DefaultButtonModel.fireActionPerformed(DefaultButtonModel.java:387)
    at javax.swing.DefaultButtonModel.setPressed(DefaultButtonModel.java:242)
    at javax.swing.plaf.basic.BasicButtonListener.mouseReleased(BasicButtonListener.java:236)
    at java.(Component.java:6216)
    at javax.swing.JComponent.processMouseEvent(JComponent.java:3265)
    at java.(Component.java:5981)
    at java.awt.Container.processEvent(Container.java:2041)
    at java.(Component.java:4583)
    at java.awt.Container.dispatchEventImpl(Container.java:2099)
    at java.(Component.java:4413)
    at java.awt.LightweightDispatcher.retargetMouseEvent(Container.java:4556)
    at java.awt.LightweightDispatcher.processMouseEvent(Container.java:4220)
    at java.awt.LightweightDispatcher.dispatchEvent(Container.java:4150)
    at java.awt.Container.dispatchEventImpl(Container.java:2085)
    at java.awt.Window.dispatchEventImpl(Window.java:2475)
    at java.(Component.java:4413)
    at java.awt.EventQueue.dispatchEvent(EventQueue.java:599)
    at java.awt.EventDispatchThread.pumpOneEventForFilters(EventDispatchThread.java:269)
    at java.awt.EventDispatchThread.pumpEventsForFilter(EventDispatchThread.java:184)
    at java.awt.EventDispatchThread.pumpEventsForHierarchy(EventDispatchThread.java:174)
    at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:169)
    at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:161)
    at java.awt.EventDispatchThread.run(EventDispatchThread.java:122)
看见过很多这样的问题，我也照着他们的方法去试了，我的数据库是sql server 2000 SP3版本，端口1433也打开了，还是不能解决问题，求教各位大哥大姐，不甚感激！！！

protected static String dbClassName = "com.microsoft.jdbc.sqlserver.SQLServerDriver";
    protected static String dbUrl = "jdbc:microsoft:sqlserver://localhost:1433;"
            + "DatabaseName=db_JXC;SelectMethod=Cursor";
    protected static String dbUser = "sa";
    protected static String dbPwd = "";
    protected static String second = null;
    public static Connection conn = null;
    static {
        try {
            if (conn == null) {
                Class.forName(dbClassName).newInstance();
                conn = DriverManager.getConnection(dbUrl, dbUser, dbPwd);
            }
        } catch (Exception ee) {
            ee.printStackTrace();
        }
    }
帮我看看有什么问题吗？

驱动包应该没问题啊， ，你看看，JDBC驱动包我一直都是用的这个..

TCP/IP也启动了

非常感谢楼上各位大哥的帮忙，正如6楼所说，把数据库升级到SP4就可以了，不过我还有一个问题，SP3为什么不行呢，我以前也做过一些小练习，一直都是用的SP3版本啊，为什么这个会要求SP4呢？