Can I ask a R5 problem?

Our client users often got below error when they opened mail which one day ago.“The object store that is used by this note was not found. Run the object store COLLECT task on this database.”

I have referred to below link, and this article mentioned “This is referring to Lotus Notes Shared Mail.”, but we didn’t set up Shared Mail so problem is still existing.

http://goo.gl/iH4trV

Could you give me some advises to solve this problem? I am sorry about making this post in this Release type.