Admin Page Logo switched back

Something caused my admin page logo to switch back to the WP logo. Using "inspect element" I saw that it was pulling wp-includes/images/blank.gif instead of logo.gif, which is what I recall my logo being named. Is this something that has been triggered by an upgrade to WP 3.04 or something else? How do I fix it? I tried replacing blank.gif with my logo but then noticed some unintended icons showed up as my logo. Upon inspecting the original blank.gif file, I noticed it is a transparent image. What to do?