Error -121 (cannot write log record) on update in Informix SE 5.01 in a Transaction

Informix SE 5.01 seems to have a problem with some kind of transaction. As reading a table, we update each rows of the same table, one row at a time. If we commit after each update, no problem. In the case of a global transaction (commit after the last updated row), we got the error 346 followed by Isam error 121. The number of rows updated is about 300 and enough space is available for Informix Logs. If you are award about known problems, thanks to you to help us. Implicit software Corporation