Am I safe? About ransomware

Tepsu

I encountered this problem: browser (Firefox) got locked to a website looking like a "police thing" and had text about me breaking the law etc. I could open other tabs so I googled some info. After reading some tips, I closed the browser from taskmanager (end process). Then I scanned my pc with Malwarebytes (found nothing), and then with F-Secure Online Scanner (found nothing). I also checked registry for signs of "Reveton" and "Urausy" like it says on the manual removal instructions, but found nothing.

 

So... Do I dare to log in to websites/games or do online shopping for example?

 

PS: I'm using Win7, if that matters.