Most likely, it’s time to upgrade your instance of wordpress (given their releases are every couple weeks). The new built-in automatic upgrade works if you make your blog owned by the apache user, but if you have any local changes, they get blown away by the upgrade. If you use subversion, your changes stay AND you get the security patches. To install via subversion, first follow these steps.

Before you upgrade, always backup your database and blog code:

mkdir -p ~/.archive
mysqldump --opt blog | gzip > ~/.archive/blog-$(date '+%Y%m%d').sql.gz
cd ~/public_html 
tar czf ~/.archive/blog-$(date '+%Y%m%d').tgz blog

Then upgrade. Note that switching from 2.7.1 to 2.8 isn’t just a “svn switch” — you must svn update first.

cd ~/public_html/blog
svn update
svn sw http://svn.automattic.com/wordpress/tags/3.0.3/

The next time you hit the wp-admin page, it will upgrade the db and you’ll be done.

Note that if you see

svn: 'http://core.svn.wordpress.org/tags/2.8.6'
is not the same repository as
'http://svn.automattic.com/wordpress'

you should use this svn sw command instead:

svn sw http://core.svn.wordpress.org/tags/3.0.3/