I just discovered SilverStripe (I'm a Drupal/Joomla! junkie) and I installed it on an instance of Uniform Server to try it out (www.uniformserver.com). I had a bit of a glitch with modRewrite. Uniserver installs with modRewrite enabled but SilverStripe doesn't seem to recognize it well out of the box. I got permission errors. Some research on the Uniserver forums yielded a suggestion that resolved the problem for me and the solution might be useful in other cases as well.
In the .htaccess file of the SilverStripe web root, you'll see the following lines at the top:
### SILVERSTRIPE START ###
RewriteEngine On
Replace this with (insert a line):
### SILVERSTRIPE START ###
Options +FollowSymLinks
RewriteEngine On
Hope this helps someone.