Major web sites have been targeted by criminals using malware in advertisements. Simply by browsing to a site your PC could become infected. And some of these criminals are intent on encrypting all of your files making them unreadable. If you don't have a good backup, you may have to pay a hefty ransom to get them unencrypted.
Don't be a victim. Install Chrome and one of these add-ons: AdBlock, AdBlock Plus, or uBlock Origin.
Also, please make sure you have a good back-up of your data. One easy way is to store all of your files in a folder that is backed up by an online storage service, like Google Drive, Jungledisk, or DropBox. There are many others as well but pick one that offers versioning on all of your files. (Note: do not use OneDrive as it currently only offers versioning on Microsoft format files.) Then log out of the service after it is done syncing, usually indicated by the tray icon, so the online files are protected.
If you have too much data to use an online solution or you don't trust the long term security of your online credentials, get an external USB Drive, connect it to your PC and turn on File History in the control panel and also run a complete Backup (Control Panel > Backup and Restore > Set up backup). Disconnect the drive after all files are backed up.
A periodic full backup to an external drive that is then disconnected is one of the best solutions for home users. However, if you connect your drive or log into your online service while an encryption malware is on the loose on your system, it will encrypt those files too. The advantage to the online services is that they keep older versions of your files and even if the most recent version is encrypted, you may be able to restore the previous version. For businesses or sophisticated home users, there are many other data redundancy solutions that can be employed.
If you need help please give Iowa PC Fixers a call.