You do not have the level of access necessary to perform the operation you requested. Please contact the owner of the record or your administrator if access is necessary.
I have checked the object-level permissions for this user profile - it has Read, Create and Edit permissions on Case Object.
What other security settings do I need to verify ?
Since the user is a high volume customer protal user, the sharing settings are to be done in the customer portal setup page !
I also have a high volume customer portal user that is getting those same error messages. The Help articile https://na5.salesforce.com/help/doc/en/customer_portal_setting_light_users.htm#topic-title
seems like a good solution to grant high volume users more access to additional case objects. However, my company is on Professional rather than the Enterprise, Unlimited, and Developer Edition and it looks as if this functionality is only avalible to those licences.
Any suggestions for those on Professional Edition to deal with this issue? Aside from telling my customers to stop opening up too many support cases :).
Manager Client Support