We are switching to Windows Server 2008 R2 64bit servers and are seeing some issues. Our windows services are throwing "System.AccessViolationException" exception in the windows event log. We never had this issue on our old windows 2003 32bit servers. The only app change was a recompile as a 64bit app. I don't know if it's a code issue, or a server setup issue. Anyone have any ideas why this would happen? Here are two of the stack traces. Application: MyApplication1.exe Framework Version: v4.0.30319 Description: The process was terminated due to an unhandled exception. Exception Info: System.AccessViolationException Stack: at Devart.Data.Oracle.OracleConnection.BeginTransaction(System.Data.IsolationLevel) at MyApplication.AlertWorkerBase.persistErrors(System.String, System.String, Char) at MyApplication.AlertWorkerBase.StartAlertWorker() at System.Threading.ExecutionContext.Run(System.Threading.ExecutionContext, System.Threading.ContextCallback, System.Object, Boolean) at System.Threading.ExecutionContext.Run(System.Threading.ExecutionContext, System.Threading.ContextCallback, System.Object) at System.Threading.ThreadHelper.ThreadStart() Application: MyApplication2.exe Framework Version: v4.0.30319 Description: The process was terminated due to an unhandled exception. Exception Info: System.AccessViolationException Stack: at System.Threading.Thread.InternalCrossContextCallback(System.Runtime.Remoting.Contexts.Context, IntPtr, Int32, System.Threading.InternalCrossContextDelegate, System.Object[]) at System.Runtime.Remoting.Activation.ActivationServices.DoCrossContextActivation(System.Runtime.Remoting.Activation.IConstructionCallMessage) at System.Runtime.Remoting.Messaging.ClientContextTerminatorSink.SyncProcessMessage(System.Runtime.Remoting.Messaging.IMessage) at System.Runtime.Remoting.Activation.ActivationServices.Activate(System.Runtime.Remoting.Proxies.RemotingProxy, System.Runtime.Remoting.Activation.IConstructionCallMessage) at System.Runtime.Remoting.Proxies.RemotingProxy.Invoke(System.Runtime.Remoting.Messaging.IMessage) at System.Runtime.Remoting.Proxies.RealProxy.PrivateInvoke(System.Runtime.Remoting.Proxies.MessageData ByRef, Int32) at MyApplication2.SessStatsLookup..ctor(Energy.VT.Common.ApplicationParameters) at MyApplication2.TCPConnection.ClientHandler.Initialize(MyApplication2.ApplicationParameters) at MyApplication2.TCPConnection.ClientHandler.ServeClient() at System.Threading.ExecutionContext.Run(System.Threading.ExecutionContext, System.Threading.ContextCallback, System.Object, Boolean) at System.Threading.ExecutionContext.Run(System.Threading.ExecutionContext, System.Threading.ContextCallback, System.Object) at System.Threading.ThreadHelper.ThreadStart() Dan

Do you think Data Execution Prevention could cause this? Dan