Mytv sometimes hangs (1 Viewer)

[datfreak]

Hi, first of all , this is the most stable version of MP that Ive ever used- thanks for all the good work

Just a quick Q.
Im running RC1 on singleseat using mysql 5 (i could not get the microsoft one to work) and sometimes it hangs to blue screen as I select MYTV from the root menu.
I can end it in task manager- and tv server does seem affected, as it as still recording tv and doesnt miss a beat.
the error log says:
2008-05-21 19:55:26.734375 [ERROR][MPMain]: ProcessWindows exceptionystem.NullReferenceException: Object reference not set to an instance of an object.
at TvPlugin.TVHome.UpdateProgressPercentageBar()
at TvPlugin.TvGuideBase.Process()
at MediaPortal.GUI.Library.GUIWindowManager.ProcessWindows()
2008-05-21 19:55:27.750000 [ERROR][MPMain]: ProcessWindows exceptionystem.NullReferenceException: Object reference not set to an instance of an object.
at TvPlugin.TVHome.UpdateProgressPercentageBar()
at TvPlugin.TvGuideBase.Process()
at MediaPortal.GUI.Library.GUIWindowManager.ProcessWindows()

over and over and over and over.

Whats causing this? thankyou for your help