Normally Websites.It happened to me a couple of times opening websites and it happens that quick you have very little time to close the program.pressing ESC might get you out if not hit the red X.Since then I have run AVG and the resident shield should stop them from getting through.I also have A Squared with background guard running.And so far have had nothing trying to download on my computer since.Also maybe a good Firewall will help as well.If they manage to get past your Anti-virus make sure that you have a couple of good Anti-Spyware programs already downloaded.Malwarebytes free and Superantispyware are 2 of the best freebies.now all the extra security programs may make your computer run slightly slower.But better safe than sorry.
i've got away with it by not clicking any pop up and hitting restart on my lappy,when it's restarted all is ok.i've been reading about this nasty today and it seems most think that hitting cancel will stop it downloading which it obviously does exactly the opposite.
Spybot does immunise Opera. The thing to watch out for is, if you're browsing and using a search engine and you suddenly get a pop-up for AV 2009 then, don't click the pop-up but right click taskbar and select taskmanager and close the browser. Unfortunately some genuine sites can be compromised so any pop-ups with any warnings of security failure etc., do the same and 'end task' the browser. Will help to prevent these malware downloading.
You have no need to be worried if you exercise some common sense. It dowers not come form a particular or particular type of website so those who wish may continue to surf porn sites. You may receive a pop up asking if you would like a free scan or registry fix or that you have viruses. It is important that you do not agree to the scan or whatever. Once you agree no AV or antispy programme will stop the installation. However, if you are infected it is fairly easy to shift....provided steps are taken within a short space of time and malwarebytes seems to work admirably. I really would not worry too much and don't get paranoid.