I'm working heavily with query notifications in SQL Server 2005 and I 
intermittently get the following exception:

System.Collections.Generic.KeyNotFoundException: The given key was not 
present in the dictionary.

No one on the Internet seems to have ever encountered this.

A partial stack trace appears below.  It's partial in that I've ommitted a 
long set of calls from our interal app framework that are orthogonal to the 
problem.

The NT user making these calls is a local administrator on the database 
server.  The calls work a lot of the time, but break and seemingly random 
moments.

We use a preconfigured SQL Server Service Broker Queue named 
QueryChangeMessages and a service called QueryChangeNotifications.

Please help.

Server stack trace: 
   at System.ThrowHelper.ThrowKeyNotFoundException()
   at System.Collections.Generic.Dictionary`2.get_Item(TKey key)
   at 
SqlDependencyProcessDispatcher.SqlConnectionContainer.ProcessNotificationResults(SqlDataReader reader)
   at 
SqlDependencyProcessDispatcher.SqlConnectionContainer.SynchronouslyQueryServiceBrokerQueue()
   at 
SqlDependencyProcessDispatcher.SqlConnectionContainer..ctor(SqlConnectionContainerHashHelper hashHelper, String appDomainKey, Boolean useDefaults)
   at SqlDependencyProcessDispatcher.Start(String connectionString, String& 
server, DbConnectionPoolIdentity& identity, String& user, String& database, 
String& queueService, String appDomainKey, 
SqlDependencyPerAppDomainDispatcher dispatcher, Boolean& errorOccurred, 
Boolean& appDomainStart, Boolean useDefaults)
   at SqlDependencyProcessDispatcher.Start(String connectionString, String 
queue, String appDomainKey, SqlDependencyPerAppDomainDispatcher dispatcher)
   at 
System.Runtime.Remoting.Messaging.StackBuilderSink._PrivateProcessMessage(IntPtr 
md, Object[] args, Object server, Int32 methodPtr, Boolean fExecuteInContext, 
Object[]& outArgs)
   at 
System.Runtime.Remoting.Messaging.StackBuilderSink.PrivateProcessMessage(RuntimeMethodHandle 
md, Object[] args, Object server, Int32 methodPtr, Boolean fExecuteInContext, 
Object[]& outArgs)
   at 
System.Runtime.Remoting.Messaging.StackBuilderSink.SyncProcessMessage(IMessage msg, Int32 methodPtr, Boolean fExecuteInContext)

Exception rethrown at [0]: 
   at System.Runtime.Remoting.Proxies.RealProxy.HandleReturnMessage(IMessage 
reqMsg, IMessage retMsg)
   at System.Runtime.Remoting.Proxies.RealProxy.PrivateInvoke(MessageData& 
msgData, Int32 type)
   at SqlDependencyProcessDispatcher.Start(String connectionString, String 
queue, String appDomainKey, SqlDependencyPerAppDomainDispatcher dispatcher)
   at System.Data.SqlClient.SqlDependency.Start(String connectionString, 
String queue, Boolean useDefaults)
   at System.Data.SqlClient.SqlDependency.Start(String connectionString, 
String queue)