Problem filling in any type of input box zero or o's fill up the box instead

Avast Free Antivirus / Premium Security
1

Problem filling in any type of input box, zero or o’s fill up the box instead of the letters I type.
If I tried to do a Google search as I start typing zero or o’s fill up the box instead.

I have run the full system scan and it detected some problems but after taking care of those plus running a boot up scan. I still have the same problem. I ran a second full scan but nothing.

Any ideas?

2
Any ideas?
Yup. Provide more details.

What os/sp?
What exact version of avast?
Any other security software installed? (or previously)
What “input boxes” do you mean?
Only on (certain) websites or also in applications?
etc.