Really Frustrating -9628 Errors

We've written several Informix stored procedures that return MULTISET as the type; the application than does a SELECT a,b,c FROM TABLE({procedurename}({parameterlist...})). And these WORK!!! But only for awhile, the next day, or after a couple of days suddenly they stop working - and they haven't been changed. They simply start to bomb out with a -9628 (type not found) error for any SQL statement like the above. We are using "IBM Informix Dynamic Server Version 10.00.UC1" on LINUX. The engine itself is perfectly stable, but attempts to use SPLs that deal with collection types fall apart after a few days. An example of a procedure that bombs has an return type like - CREATE FUNCTION p_get_equip_history(i_equip_id INT, i_event_count INT) RETURNING MULTISET ( ROW (record_id INT, equipment INT, entry_type INT, meter_reading INT, event_date DATETIME YEAR TO DAY, workorder_number INT, workorder_segment INT, charge_labor FLOAT, charge_parts FLOAT, charge_misc FLOAT, component_code CHAR(10), modification_code CHAR(10), job_code CHAR(10), description CHAR(255)) NOT NULL );.... Has anyone seen this? I've searched high-and-low but don't find much information on -9628 except to indicate that we are doing something wrong... BUT THE ROUTING WORKS,,, for awhile. Any pointers or assistance would be greatly appreciated. [demime 1.01d removed an attachment of type application/pgp-signature which had a name of signature.asc] sending to informix-list