Well, I now have a crash report:-
Problem signature:
Problem Event Name: BlueScreen
OS Version: 6.1.7601.2.1.0.768.3
Locale ID: 2057
Additional information about the problem:
BCCode: d1
BCP1: 0000000000000008
BCP2: 0000000000000002
BCP3: 0000000000000000
BCP4: FFFFF88002EA7B72
OS Version: 6_1_7601
Service Pack: 1_0
Product: 768_1
Files that help describe the problem:
C:\Windows\Minidump\012612-23946-01.dmp
C:\Users\ToshibaC660\AppData\Local\Temp\WER-40700-0.sysdata.xml
C:\Windows\Minidump\012612-23946-01.dmp files cannot be opened by Windows (even though I have 'permission'), and C:\Users\ToshibaC660\AppData\Local\Temp\WER-40700-0.sysdata.xml is obviously 'hidden' as no such folder as AppData can be found in C:\Users\ToshibaC660\
There are 32 dmp files in the Minidump folder.
Referring to the cooling - the increase in fan activity occurs when the laptop is well clear of any obstruction and there is no external sign of 'heat'. With the previous machine the shutdown seemed to occur when the batteries reached full charge, but that doesn't seem to be the case with the current machine.
I don't understand 'Does the same occur with the battery not present ?' - I thought that that was a no-no?
Edited to add:-
I found C:\Users\ToshibaC660\AppData\Local\Temp\WER-40700-0.sysdata.xml by using 'Search' but it is 'Access denied'.