One of the common the common problems with Laptop and one of the widely Laptop Repair is the laptop shutting it self off in the middle of the program.  The most common reason for this is dust in Fan Unit.  This will very true of a Older Laptop.

Check out this short film :-

Although I don’t recommend taking it apart but you could alway do it another way,  try buy Compressed Air Dust remover and blowing it into the Air vents on a regular basis this will stop the build up.

If it really bad then you could alway bring it into out Burton on Trent Branch.