In the performance settings when Optimize CSS files is selected, I get a 404. The reports section shows a 404 for example sites/default/files/ctools/css/588b003a48050c4e59cbeba2b453cb92.css not found.
I have the site running on a Mac without any issues. It's on Ubuntu. It's not a permissions issue (files dir and sub dirs have chmod 777). And the directory does exist.
Any ideas? Or has any body else experienced this issue?