David, as you know avast needs to update a lot of information
Took them over 6 months to mention that SSE2 is needed on the website.
Anyway according to the info on the site the ATOM is not supported.
Don't know if this is causing the issue or that it is something else.
I suspect it is the virtual keyboard that is causing the problem as avast tries to protect against keyloggers.
Phillip, if possible please connect a normal keyboard to that system and see if it solves the problem.