Computer crashing is almost always a hardware malfunction, or a bad/corrupted/out-of-date driver.
First update all the drivers (video driver and BIOS driver are the two I can think of). If that doesn't help, then begin running diagnostics on all of your hardware, and don't forget to check the cooling system.
The laptop has just had all of the diagnostic tests by the computer
engineer/expert and all is ok. I took it back to where i bought it.
It is a brand new laptop so should not be out of date. Would you
recommend updating the drivers however?
Yes, update/re-install all drivers.
As a general rule of computers (which has nothing to do with Lightroom), computer crashing is either drivers or hardware.