Message 131-183

Dear Experts/Gurus,

This strange error message is confusing problem to me. It is "This entry already exists in the following tables “Alerts” (OALR)” [Message 131-183]". I have actually created a query and add it in the field query on table OALT. I tick the active tickbox and the frequency is every 10 minutes. The priority is normal. However, the message always appears one or two days. I really do not know the solution. I appreciate your answer so much. TIA

Rgds,