functions.php breaks RSS feeds

I am using a custom functions.php file (see source) in a theme I am developing. I need the file to create the sidebars used by the Widgets plugin.

The widgets are working fine, but my RSS feed breaks when the functions.php file is included in my theme folder. If I delete the file, the RSS feeds look fine.

Specifically, I’m getting a few extra blank lines at the top of the RSS feed, which I think interferes with the document type. It comes out looking like this (I saved a copy – this isn’t the live feed).

Any idea what part of my functions.php file is causing this? I tried removing the JavaScript for the search box, as well as the Recent Posts code, but neither helped, so I put them back in.

Failing that, could it be some other issue with widgets? I appreciate any ideas you’d be willing to share.