Topic Last Modified: 2007-02-13

The Microsoft® Exchange Server Analyzer Tool includes a performance data collection engine that is used to query performance counter objects on computers that are running Exchange 2000 Server or Exchange Server 2003. The performance data collection engine collects data from the Output Queue Length performance counter of the Network Interface performance object to analyze performance data.

The Output Queue Length performance counter shows the length of the output packet queue, in packets. The Exchange Server Analyzer reports the maximum value for the performance counter during the collection interval. If the average value exceeds 10, the Exchange Server Analyzer displays an error.

This error usually indicates that the server is experiencing periods of unresponsiveness, causing mail flow to slow down or stop. Additionally, Outlook clients who connect to this server may receive the RPC cancel Request dialog box.

The following are some of the possible causes of this error:

In certain circumstances, on a machine running the Microsoft Windows 2000 Server operating system, the Output Queue Length performance counter may consistently show a random value that is greater than zero. For more information about the circumstances in which the Output Queue Length performance might display the random value, and how to correct this, see Microsoft Knowledge Base article 834940, "System Monitor may display high values for the Output Queue Length performance counter in Windows 2000" (

Take the following steps to resolve this error:

Consider the best practices in the following articles: