OP here.

Since I am a very small business (Sole Proprietor) I needed to stay on track before I got derailed.

I purchased a new laptop just to run QB. It runs fine using the file from the troubled machine. In fact my file is readily available on either machine via OneDrive.

I have been able to overcome the system crashes by wiping and re install of QB on the trouble machine.

I still get the Unrecoverable Error and closing of QB only on the trouble machine. Sometimes right away, sometimes while in the middle of invoicing, estimating, payroll. Totally random.

I've found that I sometimes get more time if I open QB and minimize, wander off for a bit and come back to it.

File Doctor will not open and run from the Tool Hub but will on the new laptop. I even have the File Doctor Icon on the laptop.

So for now I'm begrudgingly using a laptop to do my QB work.