jQuery UI 1.8.3 Changelog
There was a problem with the build process which generated jQuery UI 1.8.3 which caused some of the files to not contain the copyright information. Due to the missing copyright information, 1.8.4 was immediately released after 1.8.3.
If you are using jQuery UI 1.8.3, please upgrade to 1.8.4 or a more recent version.