No one solution is perfect. I use ESET at work and OpenDNS, but have still had issues on certain users computers. Why is it always the same ones? LOL
When I do have an issue Malwarebytes is incredibly useful in removing the infection. Sometimes there are specifically made removal tools for certain infections.
This sounds like what you have:
http://www.bleepingcomputer.com/viru...ing-ransomware
http://malwaretips.com/blogs/fbi-ant...ning-moneypak/