I'm working on a small site for a client and am experiencing something I've never had trouble with before. Whenever I enable Pretty URL's (and .htaccess is updated accordingly), I get logged out if I leave the homepage or attempt to edit the page. I have tried defining my BASE_URL in config/site.php and clearing the cache. Advanced Permissions are not enabled, and the problem exists across multiple users. If I disable Pretty URL's, the site works as expected. Another random bit (that may be unrelated): each time I change something in CSS, I have to clear my browser cache to notice the change. I've never noticed this before on previous sites... could it be something with the host? The URLhttp://www.maryvilletwisters.com... and the site is hosted with Arvixe, if that helps.

Thanks in advance!