A link to the MythTV subversion repository lives in the Resources section of the navigation sidebar, and is accessible from all pages on the site.
If you are going to use Subversion builds on your machine, please understand that you are venturing into the waters of alpha testing, and be prepared to cope with the more stringent expectations that will be placed upon you.
More information on how to compose a TRAC ticket that will best help the developers to identify and, possibly, work on, your problem can be found here.
Be sure to read http://www.mythtv.org/docs/mythtv-HOWTO-4.html
before visiting http://www.mythtv.org/docs/mythtv-HOWTO.html#toc5.4