I posted earlier about this problem. I just remembered, after uninstalling Avast, now if you run another Anti-Virus program like on a CD, it won’t initiate either. I was able to before uninstalling Avast. Now, I get I/O Error messages.
Possibly Remnants from Avast installation still hanging around in the OS
Have you used the Uninstall Utility?
Information:https://support.avast.com/en-ww/article/Uninstall-Antivirus-Utility