Whats the best free pop-up Blocker?

[oscargarza88]

i had one b4 but i dont now, can someone help me caus ei am receving a MAJOR invasion of pop ups!! if i leave the comp 3 mins i come back like with 20 pop ups, and im not even surfing the net!!
and i think they r the cause of m=the spyware in my comp, each time i run a spyware check i get like 500!!