Users receive a "The page cannot be displayed" error message, and "Connections_refused" entries are logged in the Httperr.log file on a server that is running Windows Server 2003, Exchange 2003, and IIS 6.0

You experience the following symptoms on a server that is running Microsoft Windows Server 2003, Microsoft Exchange Server 2003, and Microsoft Internet Information Services (IIS) 6.0:

• When a user tries to use Microsoft Office Outlook Web Access or view a Web page that is hosted on the server, the user receives the following error message:
  The page cannot be displayed.
  The page you are looking for is currently unavailable. The Web site might be experiencing technical difficulties, or you may need to adjust your browser settings.
  
  Cannot find server or DNS Error.
• When you view the Httperr.log file, you see multiple occurrences of entries that resemble the following:
  Number_Connections_refused

Notes

• You must have error logging enabled for the HTTP APIs.
• The Httperrlog_number.log file is located in the following folder:
  \System32\LogFiles\HTTPERR

This issue occurs if less than 20 megabytes (MB) of nonpaged pool memory is available on the server. When less than 20 megabytes (MB) of nonpaged pool memory is available, the Http.sys kernel mode driver stops accepting new connections.

This issue may occur in situations in which the /3GB switch is enabled in the Boot.ini file on the server.

Important This section, method, or task contains steps that tell you how to modify the registry. However, serious problems might occur if you modify the registry incorrectly. Therefore, make sure that you follow these steps carefully. For added protection, back up the registry before you modify it. Then, you can restore the registry if a problem occurs. For more information about how to back up and restore the registry, click the following article number to view the article in the Microsoft Knowledge Base:

To work around this issue, add the EnableAggressiveMemoryUsage registry entry to the following registry subkey:Then, set the EnableAggressiveMemoryUsage registry entry to 1.

To do this, follow these steps:

1. Click Start, click Run, type regedit in the Open box, and then click OK.
2. Click the following registry subkey:
   HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\HTTP\Parameters
3. On the Edit menu, point to New, and then click DWORD Value.
4. Type EnableAggressiveMemoryUsage, and then press ENTER.
5. On the Edit menu, click Modify.
6. In the Value data box, type 1, and then click OK.
7. On the File menu, click Exit to exit Registry Editor.
8. Restart the HTTP service. To do this, follow these steps:
   1. Click Start, click Run, type cmd in the Open box, and then click OK.
   2. At the command prompt, type net stop http /y, and then press ENTER.
   3. At the command prompt, type iisreset /restart, and then press ENTER.

By default, the HTTP service in IIS 6.0 stops accepting connections when nonpaged pool memory reaches 20 MB. When you enable the EnableAggressiveMemoryUsage registry entry, the HTTP service stops accepting connections when nonpaged pool memory reaches 8 MB. This condition may reduce the number of "Connections_refused" entries that are logged in the Httperr.log file. For more information about the EnableAggressiveMemoryUsage registry entry, click the following article number to view the article in the Microsoft Knowledge Base: For more information about HTTP API logs, click the following article number to view the article in the Microsoft Knowledge Base: For more information about the /3GB switch, click the following article number to view the article in the Microsoft Knowledge Base: