Possibly. Didn’t really understand the link and my TV does not have a setting adjustment for HDMI, but it gave a clue.
I just mentioned to my wife that it might be related to the HDMI connection on the TV and found out my daughter had, un-beknownst to me, plugged a spare HDMI cable into the back of the TV (Sharp Aquos) a while ago for connecting her computer to it. She had disconnected the computer but not the cable from the TV.
It seems that this has affected the HDMI-input causing the TV to reset when in HDMI mode as it were.
So thanks to garyb for responding so quickly and giving me that little bit more info I needed.