I am getting a message that reads "Your computer is infected! Dangerous infection was detected on your PC. The system will now download and install most efficient antimalware program to prevent data loss and your private information theft. Click here to protect your computer from the biggest malware threats". This message keeps popping up near the bottom of my screen every four or five seconds. How can I get rid of this popup? Once in a while an ad for an adult internet site pops up. Please help me!