It sounds as though you have a 'rogue' at the end of the timeline - possibly on another track. In timeline view press the backslash key [\]. This will show you the whole timeline. Look for something at the end that does not belong there. Don't forget to scroll up to see if you have anything on other tracks.
Insanity is hereditary, you get it from your children
Well I was about to reply that I had checked all the tracks many times (which I had) but I did the backslash and then in the video 2 track there it was, a very tiny barely visible line (about 1 frame in length, so I guess thats why I couldn't see it before). Still not sure why I could see it but not delete it in storyline but I could delete it in timeline so thats good.