I use 'Shutdown' from the main menu. The screen ends up blank except for the usual linux mint logo. The machine is then 'hung', no other options possible until I use the force restart via the power on/off key, holding it down for 4 secs. These symptoms are the same for v19 and v20. I have also noted problems when, several months ago, I selected 'Suspend'. After that I stopped using suspend at all. Hope you can help. Overall I'm very pleased with mint, its just this one irritating problem that I'd like to get fixed. Thanks for your help.
I bought the laptop new 6 years ago. So your suggestion sounds interesting. Its started me off on a whole new line of thinking. Thanks so much for that. I tested the disk with no obvious problems, but that's not conclusive. Buying a new HDD is possible but, of course another installation of mint. A bit unsure. Maybe there are other explanations? Hope so.