What did you do immediately after you saw the message?
According to this, it's a message from a rogue antivirus that is trying to infect you, and the best thing to do is close your browser and the malware popup using Control-Alt-Delete
***Microsoft Answers forum***Clicking on an "X" in the corner of the fake warning may actually install it instead of dismissing it.
The thing to Google is not prowebprotech.nl but
"Microsoft Antivirus has found critical process activity on your pc. You need to clean your computer to prevent the system breakage."
The problem may or may not be connected to epicurious.com
Even supposedly "reliable" websites can have infected ads.
Or the unwanted popup may appear long after you visited the website that was actually infected.
Be sure to delete everything in your browser cache. If the malware is being stored in there, it will keep reappearing.