I noticed that my 404 error logs are full of entries related to the Google Analytics __utm.gif file (GIF request). The 404 entries begin like this:
404 errors only happen on the WordPress portion of the site (on which the Google Analytics plugin is running). There is another portion of my site (a photo gallery) where pages are loaded with Google Analytics -- without causing these types of 404 errors.
I have searched and searched on these forums, on Google and the Google Analytics support forums, but to no avail.