Auto Update Statistics Evalution

Hi, I'm running 11.50.FC5 and I am getting the following messages in my online log when the "Auto Update Statistics Evalution" is running: 12/20/09 01:00:05 SCHAPI: Error -242 Could not open database table (informix.aus_work_info). 12/20/09 01:00:05 SCHAPI: Type: TASK, Name: Auto Update Statistics Evaluation, Location: NULL. 12/20/09 01:00:05 SCHAPI: Error -154 ISAM error: Lock Timeout Expired 12/20/09 01:00:05 SCHAPI: Type: TASK,Name: Auto Update Statistics Evaluation, Location: NULL. 12/20/09 01:00:05 SCHAPI: Type: TASK, Name: Auto Update Statistics Evaluation, Error Message: Unable to execute function [ aus_evaluator(integer,integer) ] . 12/20/09 01:00:15 DR: Sending index sysadmin:"informix".aus_work_info#aus_work_info_idx1 : Started 12/20/09 01:00:16 DR: Sending index sysadmin:"informix".aus_work_info#aus_work_info_idx1 : Completed. 12/20/09 01:00:52 Logical Log 270808 Complete, timestamp: 0x4a76d9a4. 12/20/09 01:00:52 Logical Log 270808 - Backup Started 12/20/09 01:00:52 Logical Log 270808 - Backup Completed 12/20/09 01:06:34 Checkpoint Completed: duration was 0 seconds. 12/20/09 01:06:34 Sun Dec 20 - loguniq 270809, logpos 0x24c018, timestamp: 0x4a772c28 Interval: 5797 The messages vary but are along these similar lines, they also don't appear each evening. Anyone any ideas? Cheers