I've noticed the following error coming up in my server logs, I wonder if someone could help me identify the problem

Feb 24 11:50:07 xx024 drupal: http://www.xxx.net|1267012206|page not found|87.115.xx.xx|

xx024 = servername
the final IP is my PC IP
1267012206 - this number changes for each entry

Additionally I've noticed in Google Analytics I get visitors at http://www.xxx.net/404.html?page=/index.htm&from=

I don't have a page called 404.html, I use my hosting control panel to redirect all 404 errors to index.html

Thanks for any replies