My laptop smears?

I have a laptop i wanted to download something. When I was on a website it was blocked and my antivirus program notified me that this website was infected with something with a blacklist or something. An hour later I was watching something and then there was a still image and my laptop made such a trembling noise. I could see on my frozen screen that I did not delete the tab with this virus. Is my laptop infected? Or what should I do? I'm very desperate.

Start anew. That sounds like a bug, not a virus. Viruses that make the computer unusable would be pretty stupid.