It's not a virus or even a Trojan, just a nuisance WEBSITE script that won't go away until you respond to it 150 times. . . It would work on a Windows 8 machine too. But since they don't restore previous sessions automatically... They don't revert.Unpossible - everyone knows this cannot happen to a Mac.
A friend was just asking me about malware, which term she didnt understand. As compared to a virus. I told her that malware was whatever anyone induces your computer to do that you dont want it to do. So if you look at it that way, simply clicking on a link - it even happen to me on FR once - which had been contaminated with a porno picture would qualify as "induces your computer to do that you dont want it to do."On a related topic, I should probably to to the Apple Store and get the genius (their term for tech which is crafted to be polite to the customer by suggesting that you dont have to be stupid to have difficulty with a computer) to explain to me some of the fool things I have been doing lately to cause my Mac to sometimes get the slows.Probably just too many tabs open in Safari, or sumpn.
How many icons do you have on your desktop? That is one thing that will slow down an OSX Mac. Too many and it can slow things significantly. Keep them to just Aliases of folders elsewhere on your hard drive and the problem will go away.
Also, leave your Mac on overnight. The Mac’s UNIX system does housekeeping tasks such as that memory recovery that PAengineer mentioned and defragging and optimizing of the hard drives when the system has been idle for a period. . . but if you turn it off instead of just letting it go to sleep, these never get done. Leave it turned on.