I searched through the forum but could not find a good match for his issue.
Your advice pointed me in the right direction though - as I tested out a new project, which did not have this issue.
So the problem was in my project file. Whenever I closed the old project it produced a crash dump.
I created a new project, opened the one with an issue, selected all and pasted into the new active project. I then went through duplicating the settings from the old project to new and have cleared the fault.
Many thanks and hope that this fix helps someone else if they have this issue.