Avast is messing up our computers now have an error message

I’m going to get rid of Avast because it’s constantly telling me to scan my wifi. Now the desktop, Windows 8, won’t work at all. Can’t do a thing and got this error message:
AVAST Browser Update.exe - acu_error_x86.dll missing

What the heck is this and what’s going on. I’ve had it with Avast!

UPDATE: It seems to be working now. Couldn’t do a darn thing on the desktop but had managed to get into update Avast, but nothing happened. Came back later and it said Avast needs to restart your computer, so I did, and it’s working. Avast has become very intrusive, we’ve had it forever, but I think I’m going to find something else to use.

After an update, a restart of your system is usually required.