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Who hasn't had virus problems with their computers? Thinking about that, Andrea Collazo posts [en] on Profesora de Informática an educational piece about free tools to protect computers from virus and malware. After listing various antivirus that are available and advising about its use, she shares a final suggestion:
Every malware that can infect your computer usually aims to steal your personal data, your passwords, e-mails, etc..
Therefore, if your computer has been infected, after stabilizing it, the best thing to do would be change the passwords for the services you use on a daily basis.
Remember to use safe passwords!!