The free version of the Oxygen template refers to a file that is not supplied. The Apache error log reports:
File does not exist: [...]templates/j51_oxygen/css/menus.css, referer:[...]templates/j51_oxygen/css/template.css

The file isn't in the .zip - I re-downloaded and unzipped to make sure this was not an installation problem.

The error can be avoided by placing an empty menus.css file but I wanted to let you know about the problem so you could remove the include line or provide the menu.css.

It would be great to have more menu CSS - there's a hover style but nothing to indicate the selected menu.

In any case, thank you for providing the free Oxygen template. My client's non-profit website needed a new template when they migrated to Joomla 2.5 and Oxygen was easy to adapt and is nicer than the template they were using. It is much appreciated.