Had a blank index.php screen with Permissions - advanced

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I have a concrete5 site working on my computer (localhost) that suddenly was giving me the following blank pages:

index.php
index.php/dashboard

It would keep "loading and loading" but nothing would happened.

After doing some searches on the forums, the page re-appeared after I removed advanced permissions from my site.php file:

define('PERMISSIONS_MODEL', 'advanced');

After that I was still having issues with my /dashboard/ so I deleted the contents of my .htaccess file, and turned pretty permalinks off. Then I turned it back on, and recreated my .htaccess file. Now it everything works okay.

However, can someone explained what happened? I haven't built a production site with concrete5 yet and I really wouldn't want this to happen with a live site...