连接的用户过多 导致此错误的原因是：Web 服务器忙，因通信量过大而无法处理您的请求。
用自己的电脑架设了个下载服务器;苦于是XP系统;连接数只有10;在多方找寻后 终于找到MS自己出的修改软件，现在放出来 给需要的朋友使用
我们知道Windows 2000专业版或Windows XP专业版操作系统中IIS最多允许10个客户端的连接，在Windows 2000服务器版或Windows 2003 服务器版操作系统中则不存在这种连接限制问题。
Microsoft提供了一个管理IIS的小工具MetaEdit，MetaEdit工作在Windows NT4.0 Windows 2000上，我发现它在Windows XP上也能正常工作，另外，MetaEdit只能管理II4.0、IIS5.0或更高版本的IIS。
下面教你如何利用这个工具突破Windows XP专业版IIS客户端连接限制：
首先，你需要到下面的地址下载MetaEdit，最新版本是2.2，地址
http://download.microsoft.com/download/iis50/Utility/5.0/NT45/EN-US/MtaEdt22.exe
然后执行MtaEdt22.exe按向导提示完成安装。最后，在MetaEdit中设置客户端连接限制的参数。安装MetaEdit完毕后，在开始菜单的程序组Administrative Tools下点击MetaEdit 2.2运行，出现窗口：
窗口的左边将树展开至LM--W3SVC，直接在W3SVC文件夹上单击，选择右边列表中Name为MaxConnections的项，双击后，出现对话框：
在最后Data的文本框中默认的是10，这就是Windows XP专业版IIS默认设置的最大客户端连接数了，现在你可以改变这个默认值了，我把它改为10000，注意：在Win2000 上的IIS客户端连接数最大为2000000000
光改W3SVC上的MaxConnections不管用，还要改子键1上的MaxConnections属性。
参考：百度IIS吧
(http://tieba.baidu.com/f?kz=69388057)
Microsoft 提供了一个管理IIS的小工具MetaEdit，MetaEdit工作在Windows NT4.0、Windows 2000上，我发现它在Windows XP上也能正常工作，另外，MetaEdit只能管理II4.0、IIS5.0或更高版本的IIS。
似乎很不错，但是打开下面的目录看一下会发现还是10个线程，而且改不了！
但是经过反复试验，我发现最多可以设为40，再大就变成10了，虽然提升不是很大，但一般调试40足够了，建服务器还是不要考虑xp了。
参考：MetaEdit 2.2 Is on the Job
（http://windowsitpro.com/Web/Articles/ArticleID/26923/pg/1/1.html）
For example, the LM\W3SVC\1 subkey stores the properties related to the instance 1 Web site (i.e., the Default Web site), and the LM\W3SVC\1\ROOT subkey stores the properties related to the files in the root of the instance 1 Web site. LM\W3SVC\1 has a KeyType property of IISWebServer, whereas LM\W3SVC\1\ROOT has a KeyType property of IISWebVirtualDir. As this example shows, the metabase represents the properties for the root of a Web site as if they were for a virtual directory. However, the Web site doesn't appear as a virtual directory because the Web site is at the top level in the directory structure. （1的目录下可以找到自己的虚拟目录）
The top-level keys are LM (which stands for local machine) and Schema. The LM key contains information about the local machine and is equivalent to the ADSI path IIS:\\localhost\. The Schema key contains information about the rules for setting data types and default values. Typically, you edit the Schema key only when you want to add custom properties to the metabase—a practice that I don't recommend for beginners.
If you look at the LM\W3SVC\1 subkey, you'll notice that not all the properties defined in the IISWebServer schema are configured. If a property isn't set, it has the same value as the property of the same name in the parent key as long as the parent property is marked with an inheritance flag. This concept is called inheritance. For example, LM\W3SVC\1 inherits the properties of its parent key LM\W3SVC. LM\W3SVC has a property called AspAllowSessionState, which has an Inh attribute (aka inheritance attribute). If you set Inh to 1, the sessions are on for all Web sites; if you set Inh to 0, all sessions are off. However, if the AspAllowSessionState property exists in a Web site subkey such as LM\W3SVC\1 and the Inh attribute is set to the opposite value, the Web site's Inh value of the parent key, overrides the parent's Inh value for this Web site. （继承的作用）
If you look in the LM\W3SVC\1 subkey and AspAllowSessionState doesn't exist, you can add it by right-clicking in the right pane and choosing New DWord. Then, select AspAllowSessionState from the drop-down list. MetaEdit fills the drop-down list with all the possible DWord choices. (You can add a property that isn't defined in the subkey's class, but doing so isn't a good idea because it can cause the metabase to become corrupt.) After you select the property, you need to select the correct User Type and enter the Data value. You can obtain the User Type from the property list in the MSDN Library or from the parent key. If you select the Inherit check box, the children of the key can inherit the property.
MetaEdit-Only Properties
The metabase includes many properties that you can set to perform helpful tasks or customize IIS. Only MetaEdit can set some of these properties. For example, you must use MetaEdit to set the AspThreadGateEnabled, Realm, AspRequestQueueMax, AspTrackThreadingModel, and AspQueueConnectionTestTime properties.
参考：Installing and Securing IIS Servers (Part 3)
http://www.windowsecurity.com/articles/Installing_Securing_IIS_Servers_Part3.html
A hierarchical arrangement of the metabase is clearly seen; in addition, most of the metabase keys contain the property "KeyType" which has a specific importance. The property list seen in the right pane has the following columns:
- Id this is the number identifier of the property; it is a unique attribute of the property
- Name is a name of the property; certain properties may have no name assigned
- Attributes mean property attributes; "Inh" is the most important attribute for article, since it is an advantage which makes the inheritance of key values intuitive (metabase subkeys embedded in keys with properties will inherit these properties)
- UT (User Type) indicates an application of the property, for example, a server, files, WAM (Web Application Manager), ASP applications.
- DT (Data Type) is related to the kind of data (for example, numeric, character, list of characters, binary data etc.)
- Data, i.e. the data itself.
