Have been using the free version of Avast! for about 3 years, on my laptop (aka notebook). After receiving nagware, repeatedly (I was within 27 days of expiration on my FORMER formerly current free subscription), I was about to subscribe and pay for the paid version.
But then: suddenly, I couldn't download emails via my desktop email client (Thunderbird). All the mail was there on the gmail website -- but I had to use the web interface, which, frankly, I'd never used. I always used POP.
So I deleted sercurity certificates, etc., reinstalled them, was able to receive email again in my client.
Then tonight, I couldn't send a reply. It was Avast! AGAIN.
I was terminally terminally FED UP.
I deleted Avast! PERIOD.
As a backstop/backup, downloaded/installed Microsoft Security Essentials etc. antiviris.
Oh yes, and, Avast! uninstalled, I was able to send a reply email to a colleague on my email a/c.
Bye Bye forever, Avast!