@PilgrimHiker,
I suggest getting "hardware info" ( do a search ) so you could see if the temp is being monitored. Usually that is the problem.
When my computer shutdown it is often it gets too hot. Most computers have a built security feature that will shut the computer down or put it into sleep mode when it is too hot.
80 in the summer is normal ( labtop )
70 in the winter is normal ( labtop )
My desktop is in the 60's most of the time.
I will admit my Windows XP machine will shut-down at random but after turning of the browsers that seems to solve that problem.
I use the same vender for all my machines, ( not Dell or HP ), and they seem to have a built in alarm and shutdown warning if the computer temp goes above a certain amount.
..............
If anything is a virus it is Quickbooks. It installs it's own account and no matter how much I try to clean the registery it is still there. I have to literally go into the operating system files and possible run the true
admin to remove anything. It is a pain to remove.
.................................................................................................
Malware Bytes
Smadav ( extremly strict but has many up to date definitions )
Symatic ( has many older definitions )
are some of the best outside the windows firewall system
I doubt it was any kind of virus. My mail program I use automatically filters out anything that is clearly a scam link and often reading them I find them to be poorly written and sometimes I will get an alert.