SE 4.1 vs 4.0

We're using Informix SE, SQL and 4GL, version 4.0, over PC NEC 486, SCO UNIX. We have a system with 500 programs, nearly stable. We're having plenty of bugs (added rows that we can't read via indexes, problems with indexes which key is a serial number, etc.). We heard that version 4.1 has not these, and other bugs. 1) Version 4.1 bugs are really less than version 4.0? 2) Can we upgrade the SE and NOT change the programs? 3) To change the programs, we must only compile them, or we must also change the code? 4) The Data Base must be converted? 5) Is the necessary amount of work justified? THANKS. --- Andres Marianovsky andres@dia.edu.ar