Problems with SE5.0 on ICL DRS600

Has anyone heard about problems with the v5.0 release for the SPARC based ICL DRS6000? We're a software house that writes 4GL based accounting software for various UNIX boxes, including the 6000 from ICL. Recently we've been having probs with certain programs running this version... Symptoms. --------- A simple query like select count(*) from aaa,bbb where aaa.ref = bbb.ref and aaa.desc = "AR" and aaa.rowid = 999 The table names have been changed but the select is the same, a bloddyeasy query really!, but if you run it the engine terminates. The same query works OK without the rowid bit. Corrupt indexes/tables I hear you say - no, because the same select fails against 2 other databases. BCHECK says the files are OK, but just in case, we unloaded the data, droped the tables and re-created them - no joy. We fixed this particular problem by switching to the 5.1 engine, but this also has bugs (says INFORMIX), and is a little flakey... ( .1 syndrome?? ) Can you help...... Cheers Chris.