Getting Error while publishing

<?xml version="1.0" encoding="utf-16"?>
<ErrorReport xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:xsd="http://www.w3.org/2001/XMLSchema">
<FirstName />
<LastName />
<EmailAddress />
<UserId />
<MachineName>UT517612</MachineName>
<HardwareId />
<Message>Object reference not set to an instance of an object.</Message>
<StackTrace> at Articulate.Design.Publish.Player.PlayersFactoryBase`1.set_CurrentPlayer(T value)
at Articulate.Design.Publish.Player.PlayersFactoryBase`1.Articulate.Design.Publish.Player.IPlayersFactory.set_CurrentPlayer(IPlayerData value)
at Articulate.Presenter.Model.Project.af(IPlayersFactory A_0)
at Articulate.Presenter.Model.Project.CreatePlayersFactory()
at Articulate.Design.Project.get_PlayersFactory()
at Articulate.Design.Project.get_PlayerData()
at Articulate.Design.Project.SetPlayerTitle(String newTitle, Boolean userDefined)
at Articulate.Design.Project.Articulate.Model.IProjectMetadata.set_Title(String value)
at bdq.eq()
at bdq..ctor(Guid A_0, String A_1, String A_2, Cache A_3, IWebBrowserControlFactory A_4, IVideoEditorFormFactory A_5, ChromiumVideoPlayer A_6)</StackTrace>
</ErrorReport>