Possible cause and solution:
The Microsoft Loopback Adapter can affect local check in and check out of concurrent activations. Review the Microsoft hotfix 979612 which can improve TCP loopback latency and UDP latency in Windows Server 2008, Windows Server 2008 R2, Windows Vista, and Windows 7 to see if it applies to your system.
From the Home page, click Manage Activations > Find available activations, and make sure each path in Path to Activations is correct. Also, remove any computer from the list that is no longer being used to provide activations and make sure that the order of the locations is optimal for providing activations without delays. Click Up or Down to reorder the activation paths.
Click Advanced >Refresh This Server. If the Server state is Stopped, click Refresh.