If you give me ftp access to the server and a url I can debug it.
I'd start by adding a die("here"); statement on top of the page and then move it down a few lines at a time until I didn't see it any more. That would help narrow down the exact line of code causing the error. Once you have the line of code narrowed down, then you can hypothesis about why it causes an error... we just need more information than a general error.