WordPress error message – URGENT help please!!

The first is a typical 404 error if you have not created a favicon for your site. I believe that some browsers (Firefox et al) automatically look for the favicon and it may return a 404 if you don’t have one.

The other error appears to be a standard 404 message. I don’t really see evidence of malicious intent.

As far as why you’re getting emails about this, you may have a plugin installed that automatically notifies you of 404 errors. Check your installed plugins.