The other day I was browsing a streaming site and an Avast message popped up saying it blocked an attempted infection. After this Windows Update wanted to restart my computer. This happened twice with seemingly no update taking place as there was no message being displayed during shut down and start up. A third time Windows Update wanted to restart my computer and again I obliged but when the computer was shutting down the Update text being displayed was unfamiliar. After I was able to use the computer again I checked the Windows Update history and everything seemed legit. It was displaying a number of failed and successful updates going back weeks but the times for the updates I suspected might be virus related appeared to be from Windows after all.
So my next step was to start scanning my computer. I did several full system scans with Avast, Malwarebytes, and Spybot S&D and nothing malicious showed up with any of them. I was still worried though because my internet was going very slow which was strange. I use my computer to play poker and sometimes for banking so I don't really want to take any chances so I decided to take it to a local computer shop to have it reformatted. My question is when I get the computer back should I do anything to make sure it's clean? I will never surf a website I don't trust again so hopefully the chances of being infected in the future are nil. As far as system specs go I run Windows 7 and use Avast as my antivirus.