Yesterday, Avast prompted me to update, and I did. Then it wanted to restart, so I said okay. A while later I came back to my computer, totally black screen, dead. I tried restarting again, same thing. I have a dual screen setup, and I finally turned on the second monitor, and there was a notification that the computer could try to fix the start-up error. I said okay, not holding out much hope, but it did, and life got back on track. The Avast update caused the problem but didn't even apply an update because I'm still getting notifications to do the same update, and I'm afraid to try it again.
I'm a first time Avast customer, have been using Symantec and Kaspersky in the past, and until now was very happy with Avast. Now I'm not so sure. I never had an issue like this with the other antivirus softwares.