Useful tool I would like to remind.

Content box: free HTML module for Prestashop that facilitate the way to create advertisement modules or other specific needs; http://contentbox.org/

Actions to clean cache on Prestashop:

1. Advanced Parameters > Performance > Cache >  Clear Smarty cache & Autoload cache
2. Layered navigation block > Indexes and caches

Check if your site is down only for you, or if it’s down for everybody:

http://www.downforeveryoneorjustme.com/