When you say simultaneously do you mean real-time protection from both at the same time?
Yes, if your PC has enough resources to run both of them simultaneously and they will work with each other.
I understand that none of the programs are bullet-proof, but until this happened I never realized how UNbullet-proof they are. In the last few days I've run a ton of different scanners. None of them found everything. This one would find something and miss something. That one would find something and miss something.
That's not abnormal. That's why I use several different anti-spyware/anti-virus programs
I am curious about something. I didn't downloaded anything. Or get any emails with attachments. The only thing I can imagine out of the ordinary is that I followed a link to a site that had one of those BS pop-ups. Is that the likely origin of my problems? If so, short of limiting my web surfing is there a way of preventing (or reducing the risk of) it from happening again? Would switching to Opera from FF help any?
I do appreciate your time with this.
I use Firefox almost exclusively. I also use the ad-blocker add on. That helps. But, for every fix that is done by the software makers, there are virus writers that develop viruses that will circumvent the fixes. I've done something as trivial as going to a lyrics site and caught a virus. Even macs are no longer safe from viruses. I don't know what to recommend, as in my experience, no anti-virus program will catch everything.
Here's some things I use:
CCleaner
Malwarebytes
Avast
AVG
Spy Bot Search and Destroy
whatever free online scans I can find. (Many free online scans will locate the problems, but not all will fix them for free.) I'm computer literate enough to be able to track them down with a little help and get rid of them.
I did use the trendmicro trial version for a while, but when the free trial ran out, I uninstalled it. Trendmicro worked pretty well, especially the pay version and it didn't seem to hog a lot of resources, unlike Norton or McAffee.