Hello and welcome. It may have been a Window Update The come out on Tuesdays. You can chek Windows update history.
But First you need an AV. I am going to suggest you install and run this first.
Click here install the free •Antivir
...I use this.
Let me know what happens after that.
Is this an XP machine?
What Firewall is on?
Please post the Malwarebytes log
The log is automatically saved and can be viewed by clicking the Logs
tab in MBAM.
Copy and paste the contents of that report in your next reply. Be sure to post the complete log to include the top portion which shows MBAM's database version and your operating system.
Also the AVira antivir log,thanks.