Fatal error: Class 'ctools_export_ui' not found in views/plugins/export_ui/views_ui.class.php on line 13

Hi,

Updating to 3.5 gave me the above error. I have tried reverting to the prior version and also re-copying the current versions of vies and ctools but still get the above error. I've searched for similar errors but don't see quite the same situation elsewhere and the fixes suggested elsewhere (including re-copying the modules and flushing the cache) don't seem to have helped.

Any ideas?