Hi folks. My computer is a Mac, version 10.7.5
It's been runing slowly for a long time, and getting worse. I tried to fix it myself, and that worked for a little while.
Today it went berserk while I was on Youtube. It began to open widows, etc - and a window opened saying that I had a virus that was a security issue and included number to call for help. Now the computer keeps playing an "important security message" in a female voice through the speakers. I'd like to get control of my computer back. Thanks in advance for the help!