I spent weeks for figuring out what causes one of my Dell Latitute E7440 Corei7 Touch Screen Laptop for shutting down unexpectedly, randomly and frequently two or three times in a day.
I hope this will help many users who are not figuring out the solution for fixing the issue.
I opened my laptop back panel and found some solid bunch of dust particles in heat exhaust fan. I clean them with air blower lightly and issue permanently solved.