NullReferenceException in SqlTransaction.Zombie()

[buttslapper]

Hi,

Recently we discovered in our production server this kind of
exception :

We are wondering what causes the transaction to be zombied, and why do
we get a nullreferenceexception in this method ? As you will see in
the call stack, at every 5 minutes (timer), we are inserting data in a
transaction. In a day, we can have 2-3 occurence of this problème.

1) Exception Information
*********************************************
Exception Type: System.NullReferenceException
Message: Object reference not set to an instance of an object.
Data: System.Collections.ListDictionaryInternal
TargetSite: Void Zombie()
HelpLink: NULL
Source: System.Data

StackTrace Information
*********************************************
at System.Data.SqlClient.SqlTransaction.Zombie()
at System.Data.SqlClient.SqlInternalTransaction.ZombieParent()
at System.Data.SqlClient.SqlInternalTransaction.Zombie()
at System.Data.SqlClient.TdsParser.Run(RunBehavior runBehavior,
SqlCommand cmdHandler, SqlDataReader dataStream,
BulkCopySimpleResultSet bulkCopyHandler, TdsParserStateObject
stateObj)
at
System.Data.SqlClient.TdsParser.TdsExecuteTransactionManagerRequest(Byte[]
buffer, TransactionManagerRequestType request, String transactionName,
TransactionManagerIsolationLevel isoLevel, Int32 timeout,
SqlInternalTransaction transaction, TdsParserStateObject stateObj)
at
System.Data.SqlClient.SqlInternalConnectionTds.ExecuteTransactionYukon(TransactionRequest
transactionRequest, String transactionName, IsolationLevel iso,
SqlInternalTransaction internalTransaction)
at
System.Data.SqlClient.SqlInternalConnectionTds.ExecuteTransaction(TransactionRequest
transactionRequest, String name, IsolationLevel iso,
SqlInternalTransaction internalTransaction)
at System.Data.SqlClient.SqlInternalTransaction.Commit()
at System.Data.SqlClient.SqlTransaction.Commit()
at Notifications.NotificationService.CreateNotification()
at Webservices.Global.StartNextTask(Object notused)
at System.Threading._TimerCallback.TimerCallback_Context(Object
state)
at System.Threading.ExecutionContext.Run(ExecutionContext
executionContext, ContextCallback callback, Object state)
at System.Threading._TimerCallback.PerformTimerCallback(Object
state)