clean urls are supportet, but not working if enabled

I use drupal 6.6 on a host and had to deactivate *Options +FollowSymLinks* that that drupal runs
# Follow symbolic links in this directory.
#Options +FollowSymLinks

On the clean-url page */?q=admin/settings/clean-urls* drupal tells me that
*Your server has been successfully tested to support this feature.*

But if I enable clean urls I get a

1. broken theme
2. Access denied without beeing able to relogin.

Any ideas what to do?

Thanks Robert