You can try to run System Restore and rollback your computer to a time prior to the last AU update coming in and being installed. This type of message usually occurs when you click on an item in Search (Cortana) or in a folder using File Explore that has been associated with a Microsoft E-mail program such as Windows Live Mail or MS Outlook *any version*. Do you use either of these E-mail programs on your computer? Were you using either of these E-mail programs to read your E-mail prior to the AU update?
If this doesn't work, then it's very likely you have a virus/malware infection.
Use whatever your primary AV (Antivirus) is to scan/remove all viruses found. Additionally, if you are not using either of the E-mail clients above to read your E-mail but rather a webmail type program via a browser such as Yahoo or Gmail you'll need to check for spyware viruses as well. Download the free
MALWAREBYTES from
malwarebytes.org and scan/remove all found spyware viruses.
Power off your computer 5 min. after you've done both AV and AS (Antispwyare) scans and see if the warning box comes back. If it does not, you have 1 or more viruses/malware causing that message and if gone, it's now fixed.
If the problem persists, you'll need to post back for further instructions such as hardware testing and more aggressive software repairs.
Also, if that is the case you'll need to provide us with more information about your computer, such as Make/Model, is it a desktop PC or laptop? Is it an OEM computer (Acer, Asus, HP, Dell, Toshiba)? Did you build it yourself (self-built rig) or did you buy it from a shop that built the computer to your specs? If so, we need complete hardware specs: Make/Model of Motherboard, Make/Model CPU chip, Make/Model GPU card, Make/Model of RAM sticks, Make/Model/Wattage of PSU.
Thanks,
<<<BIGBEARJEDI>>>