Why did my tablet stop switching to widescreen when connected to my TV through HDMI? I have a tablet PC running Android v4.0.3. Up until recently, when I connected it to my TV it automatically switched to widescreen (16:10) format. 

Something has changed, and now it always displays as the old narrow screen format. There doesn't appear to be a setting for this on the tablet.

It's a NATPC M0009 in case that makes a difference. 

Has anyone had a similar issue, or can anyone point me towards a solution?
Perhaps you've locked the format on the TV instead of setting Auto-switching. Check the TV settings.