I have at least 8 computers on the bench cleaning up viruses, malware, spyware and adware. It just seems that no matter where you go you can get infected in one way or another. I have had many times where I have gone to a website and all of the sudden I am being told I am infected and they want me to click on something. Well the best thing is don't click on anything. One choice is to just plain shut the computer down properly. Next reboot and run some free programs like rogue killer and free malwarebytes. I would also suggest running adw cleaner and the junkware removal tool. These are all free from bleeping.com. I would suggest running all these in the safemode with networking.
Many people always ask why didn't my antivirus software catch the virus. Well the simple truth is that no virus is 100% at stopping an infection. The best protection is what you as a consumer can do yourself to prevent a virus from infecting your computer. That old saying an ounce of prevention is worth a pound of cure still holds true. Basically make sure you have good up to date antivirus software such as kaspersky or webroot antivirus software. I would also make sure you are backing up your data and system in one way or another.
When choosing to back up a system you do have some different choices. One choice is to use something like carbonite where your system backs up to the cloud. Just make sure what package you have with carbonite. Generally choose a package where it makes a system image and backs up your data as well. The other choice is to purchase a 1tb or 2tb external hard drive and use the backup program in the control panel for windows 7 or windows 10. If you are using windows 8 or windows 8.1 you can use the file history in the control panel. You will also find in the lower left corner of that window there is a choice to manually make a system image of your particular system. One item to be aware of is that the system image is only for your computer. It can not be installed on a different computer. This is because all computer have different motherboards and different chip sets. I have seen technicians try this and fail almost every time.
So remember to make sure you have good up to date antivirus software and have a good back up plan.