Cannot edit or add product after install

I have ver 1.3.7 installed, I imported the catalogue data from another zencart site and everything appeared to be fine, but I am unable to edit my products, or add new ones, when I click the preview button after editing a product I get this error:

Warning: main(includes/templates/template_default/templates/tpl_403_default.php): failed to open stream: No such file or directory in /home/saveonci/public_html/includes/templates/template_default/common/tpl_main_page.php on line 119

Warning: main(includes/templates/template_default/templates/tpl_403_default.php): failed to open stream: No such file or directory in /home/saveonci/public_html/includes/templates/template_default/common/tpl_main_page.php on line 119

Fatal error: main(): Failed opening required 'includes/templates/template_default/templates/tpl_403_default.php' (include_path='.:/usr/lib/php:/usr/local/lib/php') in /home/saveonci/public_html/includes/templates/template_default/common/tpl_main_page.php on line 119

Does anyone cleverer than me have any suggestions as to what might be wrong?

I have ver 1.3.7 installed, I imported the catalogue data from another zencart site
What ver of Zen Cart was the imported DB from?

the catalogue was from ver 1.3.5

After loading the 1.3.5 DB to this 1.3.7 install - Did you re-run zc_install to upgrade the DB?

Yes I did, I have quite a fe zen sites and whilst I am not a programmer, I can generally find my way around, lol, but this one has me totally stumped.

If you have a backup of the DB before you applied the 1.3.5 DB try restoring it - I suspect that this did not work before as the error msg is indicative of missing/corrupt files

Yup tried that, did not help.

Yup tried that, did not help.
This is not at all descriptive

Tried what?

If applying the orig DB - then were you able to add product?

Try overloading from the correct distro - all the cart files - preferably with a good FTP client that reports failures like filezilla