Issues moving Codigniter from Windows server to Linux based server

The directories do exist. There are images in them which display on the site.

NO idea if it has debugging. After some searching, came up with http://dojotoolkit.org/

How would I try without session?

After what you said, and my experience with these sites, I am guessing it could also be a missing capital letter at a start of a file.

I spent hours combing through files to get the site working when I first moved it from the windows server. There are a mixture of capitalised and uncapitalised files right through the site.

Garry Cross, Web Design, Hosting & Domains
Garry Cross Personal Computers (GXPC)