Changing to Classic template still gives the same problem. I also upgraded to V1.3.6 but made no difference.

Can I confirm when you say reload the files, you mean download the whole Zen Cart, find the files, and ftp them individually to the server? Or is it something I do within the admin console? Sorry if it's a dumb question because I got Zen Cart from my hosting company and it was installed through Fantastico, so I never unpacked any files myself.

Thanks!