Interesting I just get same problem but I use zennoposter 4. It started today, yesterday everything works perfect. I get lot of non critical errors hire are cupl last rows.
2013-11-22 20:51:10.3984|ERROR|Failed to start the base|System.NullReferenceException: Object reference not set to an instance of an object.
at ZennoLab.ZennoPoster.Tasks.Threads.ServerBase.Run(Boolean& success)
2013-11-22 20:51:10.4134|ERROR|Failed to close the process of the base|
2013-11-22 20:51:10.4134|ERROR|Failed to start the base|System.NullReferenceException: Object reference not set to an instance of an object.
at ZennoLab.ProjectMaker.Debug.DebugBase.Run(Boolean& success)
2013-11-22 20:51:10.4144|ERROR|Failed to close the process of the base|
2013-11-22 20:51:10.4134|ERROR|Failed to close the process of the base|
2013-11-22 20:51:10.4144|ERROR|Failed to start the base|System.NullReferenceException: Object reference not set to an instance of an object.
at ZennoLab.ZennoPoster.Tasks.Threads.ServerBase.Run(Boolean& success)
2013-11-22 20:51:10.4134|ERROR|Failed to start the base|System.NullReferenceException: Object reference not set to an instance of an object.
at ZennoLab.ProjectMaker.Debug.DebugBase.Run(Boolean& success)