Completed 10 full Memtest passes with no errors, so proceeded to commence the Malware route. Dowloaded a number of suggested pieces of software and ran a number of operations, however the machine was getting noticably slower by the minute. Therefore, and with much concern, I lifted as much data as possible and have gone for a full 'Factory Reset' My concern was of course that the problem(s) might still prevail. Anyway, the reset is complete and the laptop is going like the preverbial again!!
Can I once more and most sincerely say 'A VERY BIG THANK-YOU' for your assistance over the last few days. I'm just sorry that we were unable to nail what was actually causing the problem.