On my Unix machine whenever I did an “svn update” and files were actually updated, the permissions would change, rendering them inaccessible to the httpd process, therefore 403 Forbidden errors in the browser.
After much searching that yielded a lot of results about storing executable flags in SVN using propset. This didn’t help as I didn’t want it to be executable, just world readable. Turns out the problem was in my .profile, my umask setting was 077. Changing it to 012 solved it for me. Note: 012 makes files you create group writable.
Snippet from my .profile
#umask 077 umask 012 export SVN_SSH="ssh -l olore" export EDITOR="/usr/bin/vi"
Read more about umask on Wikipedia