I currently have BitDefender as my main AV, and I use MalwareBytes for on-demand scanning. I like to do full system scans with each of these fairly often. (Probably once a day.)
I also like to use ESET Online Scanner, once a week or so.
So far, I haven't found anything, but something strange happened, when I tried to start up ESET, I got an "Unexpected Error 101" when downloading the definitions. Then I tried again, and I got a different error immediately (the beginning where you select the check boxes), I forget exactly but I think it mentioned something about "Unsupported Operation" then opened the online scanner program window and it was blank.
I rebooted my PC, and it ran fine. But I'm just wondering if anyone knows, what could have caused it?