I bought a used computer from a friend. He had installed AVIRA antivirus prior to the purchase & stated AVIRA was a very good "free" antivirus program. It had been two years & Avira found NO viruses until about month ago...when I got this big error message, with audio screaching over the computer's internal speaker that stated my computer was infected with a Trojan & "would you like to clean it?" including a button to press to do so. However, the button was disabled. There was also an "upgrade" button. So, in a panic I pressed it...It also did nothing. Then I got a new, more concerning error message from Avira that stated, "14 contacts in your email have been sent worm infected files!" Frantic, I tried to uninstall Avira-that function was also disabled! (later that evening I got a call from a male business contact who was very confused as to why I would send him an email infected with an invitation to purchase Cialis/Viagra!". He implied I was coming on to him-OMG Really? Viagra, Totally Embarrassing! ) In an attempt to stabilize, I went to Avira's website & downloaded the free "Premium" 27 day version. Thankfully, I was then able to remove AVIRA completely from my computer. What a NIGHTMARE! If you don't update during the trial period, Avira will self- infect!!! Consider yourself WARNED!