SQL Error (-211) -- Bugs or What ?

Ho ! I had the following sql that is performed in non system database: select odb_dbname from sysmaster:sysopendb whereodb_sessionid=dbinfo("sessionid") and odb_iscurrent='Y'; time to time its work, but for some period of time it returns [Informix][OnLine Dynamic Server][_01_admin] SQL Error (-211) : Cannot read system catalog (systables). [ ISAM error -103 : ISAM error: illegal key descriptor (too many parts or too long). ] but when I'm received that error message the following query select * from sysmaster:systables works fine -- without any errors. I'm sure that none else was changing schema. My question is -- does it links with some system processes that are worked off-line and time-to-time locks system tables ? Sincerely, Alexander -- Alexander V.Didytch, Kyiv, Ukraine Data is like garbage. You better be sure what you're going to do with it before you collect it. --Mark Twain