There are always the log showing: file does not exist c:/wamp/www/favicon.ico in apache error_log. I used wampserver, why?
Do you have a reference to the favicon.ico file in your HTML source?
Even if you don't, many browsers try to access this file anyway when visiting a new page. Favicon is used when adding the website to favourites/bookmarks. Some browsers (for example Firefox) also display favicon on the website's tab on the top of the screen.
Your best bet would be to simply add an favicon.ico file with a 16x16 icon to the c:/wamp/www/ directory.