I waited until about 10am this morning, and didn't get any error messages. However, I decided to go ahead and format my computer's hard drive. I have everything already backed up, so it wasn't too difficult. I have reinstalled Avast, with the same providers. Only difference is that I did not install Windows Defender. Instead, I will use WinPatrol.
If I encounter another red pop-up error message in the next day or so, I'll post it here.
2:45pm ET update: I got the dreaded pop-up error message again. Sigh.