missing entire past reconciliations

Twice now, previous reconciliations have disappeared. This week the Feb. '08 and March '08 reconciliations ceased to exist. All those transactions were no longer cleared but all subsequent reconciliations remained. There were no previous reports available for those two months. No updates were done since the last reconciliation. Rebuilding the data did not help. I've been using Quickbooks for years and never had this happen until we did our yearly upgrade early this year. I don't know how this is possible since you can only unreconcile one month at a time in reverse order. Why does this happen and is there any way to fix it besides unreconciling all the way back and rereconciling each month again? If this keeps happening it could get very time consuming. Thanks!