I have used avast security for several years on my imac, but recently it will not complete a scan, sticking at 99% (no viruses reported) and my computer freezing so I have to press power button to shut it down. I have uninstalled and reinstalled several times, making sure any Avast files have been removed from the library, but this makes no difference. I do not have time machine running, or any external discs connected when I do th scan. I don't think I can get a log file because I think this is lost when I have to shut down the machine. Any suggestions would be welcome.
(Running El Capitan OS X 10.11.6)