Downloaded a problem I think?

I downloaded a "DVD decoder" (didn't work) onto my laptop and since then, I have had a few minor changes. One, the browser was automatically changed to "bing" and the other, I've noticed (most often) on facebook, it no longer shows certain photographs. It's not like the file is too big, I know this, because I had the same profile picture for 2 years and now all it shows it something that looks like a thumbnail (not an X). If I click on it, it will show the picture, but it has to be selected manually. I did perform an AVG virus scan with 1 result and a few corrupted files, which were removed. However, I'm still having the picture issue. Any solutions?