You have a discussion board list and you create a new view based on the Flat template. In the Folders section of the view settings, you select either the "In all folders" or the "In the top-level folder" options. The following error occurs:
Attempted to use an object that has ceased to exist. (Exception from HRESULT: 0x80030102 (STG_E_REVERTED))
This is expected behavior. The "In all folders" and "In the top-level folder" options are not valid for a Flat view in a Disscusion Board list at this time.
Use the default "In folders of content type" setting in the Folders section when you create a view based on the Flat template.