On a heavily-loaded computer that is running Microsoft Office Live Communications Server 2003, you may experience all the following symptoms:

• Multiple Windows Messenger users receive error messages that indicate that the computer is busy or unavailable when they search for a contact.
  
  Note Sometimes, the search is successful, but it takes a long time for the search results to be returned.
• Search requests remain in the queue on the Live Communications Server.
• CPU use and hard disk use on the computer that is running Live Communications Server and on the domain controller remain at their typical levels.

This issue may occur if both the following conditions exist:

• The Live Communications Server-based computer receives many search requests from clients.
  
  -and-
• You have a Microsoft Windows Server 2003-based global catalog server.

The Microsoft Active Directory directory service in Windows Server 2003 includes the functionality to disconnect a client if it detects that the client cannot receive information as fast as Active Directory can send the information. In a scenario where you have a heavily-loaded computer that is running Live Communications Server and that receives many search requests, Active Directory may detect that the Live Communications Server-based computer cannot receive the search responses as quickly as Active Directory can send them. The Live Communications Server-based computer cannot receive the search responses as quickly as Active Directory can send them because a search response contains much more information than the search request. As a result, Active Directory might close the connection with the client (in this case, the Live Communications Server-based computer). When the connection is closed, all the pending search requests in the queue on the Live Communications Server-based computer cannot be completed until Live Communications Server reestablishes a connection to Active Directory. This issue only occurs when the channel between Live Communications Server and Active Directory is overloaded.

To work around this issue, lower the number of searches that Live Communications Server can send to Active Directory. To do this, follow these steps:

1. Start the Live Communications Server utility.
2. Right-click User Services Global Settings, and then click Properties.
3. Click the Search tab, and then type the number of searches that Live Communications Server can send in the Maximum number of outstanding requests per server box.

Important This workaround reduces the chance that the channel between Live Communications Server and Active Directory might be overloaded by search requests. However, when you configure this setting with a lower value, fewer clients can perform searches at the same time. When the maximum number of outstanding requests is reached, clients receive an error message when they try to perform a search operation. When a pending search is completed, a location is released in the Live Communications Server queue, and then an additional client can perform a search operation.

To determine if you are experiencing the issue that is described in this article, use the Performance tool in Windows Server 2003 to view the Live Communications Server performance counter information. To do this, follow these steps:

1. On the computer that is running Live Communications Server, click Start, point to Administrative Tools, and then click Performance.
2. Click the Add button.
3. In the Performance object list, click LC:USrv - 13 - LDAP Manager.
4. In the Select counters from list, add the following counters:
   Usrv - 001 - Dropped GC binds
   Usrv - 010 - LDAP search errors
   Usrv - 014 - LDAP search queue full

You may be experiencing the issue that is described in this article if the following symptoms occur while you monitor these performance counters:

• The values of one or of both the following counters increase periodically:
  Usrv - 001 - Dropped GC binds
  Usrv - 010 - LDAP search errors
  -and-
• The value of the following counter constantly increases:
  Usrv - 014 - LDAP search queue full

In this scenario, multiple Live Communications Server clients typically cannot complete search requests.