Cinthya_020 wrote:
A few days ago I called a tech support number believing it was apple, and was almost robbed $300. After realizing that the company I was speaking to was a complete scam, I hung up.
The key question is: did you give these scammers remote access to your Mac during the phone call? That could not have been accomplished without your assistance, so it should be an easy question to answer. They would have asked you to visit a website that would have downloaded something, which you would then need to install so that they could access your Mac remotely... did you do that?
If you did not give them remote access, then you're fine. The pop-ups you're getting now may simply be related to a particular bad site that you're visiting, in which case you'll need to quit visiting that site. They may also be due to some kind of adware that was installed in an unrelated incident, in which case see Niel's answer above.
If you did give them remote access, your computer should now be considered compromised. You will need to erase the hard drive and reinstall everything from scratch. See:
Tech support scam pop-ups
How to reinstall Mac OS X from scratch
Be aware that there is nothing else that you can do to guarantee that your Mac is clean if a malicious third-party has had access to it. No anti-virus software can guarantee there's nothing malicious, and even a security expert who could put his/her hands on your computer would not be able to guarantee anything 100%.
(Fair disclosure: I may receive compensation from links to my sites, TheSafeMac.com and AdwareMedic.com.)