When I look at Awstats 404 errors I see sometimes strange referrers. For example on www.mydomain.com I might see a 404 error reported in Awstats that says:
URL (not found) Referrers some-file.jpg http://www.mydomain.com/some-page.html
some-file.jpg is a file that does not exist, so it's not strange that if someone tried to reach it got back a 404 from server.
The strange part is that the referring page DOES NOT EXIST TOO, I mean
http://www.domain.com/some-page.html DOES NOT EXIST, so how could it be the referrer?
Is it some client cheating the referrer?