I have been getting these Alert! notices popping up on my screen on occasion and haven't given them much notice, just click the OK option and off they go. I am now a bit curious about them. Is someone trying to access my computer and is being stopped by my firewall? The alert appears generic, ie. not identified as being from any of my utilities. The sites identified on the alert usually appear to be government or .edu sites. Here are a couple of examples:
www.rkb.mipt.org:443 uses an invalid security certificate.