Informix must abort -- HELP SQLERROR -457

Hi all, My Informix Online 5.08 go into ABORT MODE while creating a new index on a table with about 2.900.000 rows. 17:17:52 Process Aborted Abnormally: pid=7033 user=104 us=40001ecc flags=101 17:17:52 Process Aborted Abnormally (critical section): pid=7033 user=104 flags=101It's running on OS SINIX 5.42. I set the unlimite partameters to unlimeted, and DBTEMP is big enough. I have add a new chunk for dbspace, but this error comes again. I get the SQLError -------- -457 Database server terminated unexpectedly. The database server process or thread with which your application program was working has terminated. The DBA may have shut the system down. The next most likely cause is an internal error. Look for operating system messages that might give more information. If the error recurs, please note all circumstances and contact the Informix Technical Support Department. Note: Be sure to check the ISAM error code returned with this error. If it is -129, the database server has not terminated, but simply reached a limit on the number of concurrent user sessions (see the explanation of error -129). ------------ I don't know how to get (and check) this ISAM error, but I'm sure NOT to reached a limit on the number of concurrent user sessions! Hartmut