Strange error with date field (Online 5.01)

Dear Informixers, after a problem with the system date on one of our machines (an offline backup program set the date one day ahead, which was only recognized the next day), the following problem persists on I-Online 5.01 on a SNI RM400 under SINIX 5.41C1004: One table contains a date (opdat), which is usually set by a program via the system date. The following query will result "3": SELECT COUNT(*) FROM edomorg WHERE opdat = "19.09.1996" while the following will result "0": SELECT COUNT(*) FROM edomorg WHERE opdat = "20.09.1996" The following returns "0 rows deleted": DELETE FROM edomorg WHERE opdat = "20.09.1996" while the following returns an error: DELETE FROM edomorg WHERE opdat = "19.09.1996" 240: Could not delete a row. 105: ISAM error: bad isam file format. I did the suggested "tbcheck" (-ci/-cI), which showed no error on the index. Another strange finding is: SELECT opdat FROM edomorg WHERE opdat BETWEEN "19.09.1996" and "20.09.1996"results in: 19.09.1996 19.09.1996 19.09.1996 3 rows found while the following more general query: SELECT * FROM edomorg WHERE opdat BETWEEN "19.09.1996" and "20.09.1996" results in "20.09.1996" in the "opdat" column of all three rows!!! To add something on top: SELECT * FROM edomorg WHERE opdat = "19.09.1996" (or "20.09.1996") results in "no rows found". I'm absolutely clueless as to what's happening here. Help! Regards, Richard -- +----------------------------+-------------------------------------------+ | Dr. Richard Spitz | INTERNET: spitz@ana.med.uni-muenchen.de | | EDV-Gruppe Anaesthesie | Tel : +49-89-7095-3413 | | Klinikum Grosshadern | FAX : +49-89-7095-8886 | | 81366 Munich, Germany | | +----------------------------+-------------------------------------------+