[support] Strange behaviour on localhost site

[Roger]

I have a fully updated Drupal 7 copy of our live site on my fedora 
localhost/
I log in as admin.
Problem is I cannot add a new content type. I can do so on the live site.
On the localhost home machine I get error on a blank page (Seven theme):

You are here Home >> Administration >> Structure >> Content types

Home » Administration » Structure » Content types
Content types

Remove from Default shortcuts
Individual content types can have different fields, behaviours, and 
permissions assigned to them.

Displayed url is: http://localhost/mycopy/admin/structure/types/add 
<http://localhost/eal/admin/structure/types/add> and all work the same 
as the live site.

Nothing reported in: admin/reports/dblog
Admin permissions are set correctly
No errors in /var/log.
Have restarted mysqld
Cleared browser histories on chromium and firefox

I have since taken another copy of the live site and done a fresh 
install but with the same result.

What would prevent the site from displaying the ability to add a new 
content type?

Has anyone come across this anomaly and knows where to look to fix?
Suggestions please
TIA
Roger