Error message when trying to view a category you don't have access to

Hi

We have created menu items for specific categories which are then allocated to relevant access levels. Having tested the access levels they work correctly in that users can only view the discussions within the categories they have been allowed access to. However there is a message that pops up (see screen grab) which tells the user they don't have 'sufficient privileges to perform the requested action'.

Is this a message coming from EasyDiscuss, or is it Joomla generated?

If it is EasyDiscuss, can you tell me how to change the wording?

Thanks
Katrina