intermittent -710 error

Hi. OnLine Dynamic Server 7.23.UC1 on HP-UX 10.20. We are getting -710 errors (which suggest running update statistics). I have cron jobs that run update statistics on this database every Saturday night. Scenario: User tries to update a row in table a. Gets -710 error. I run update statistics on table a and then user can do update. We also do thisfor table f and then table g. Now we try table a again and it's not working. It's only been a couple of minutes and we didn't change table a. We wait a few minutes and now it does work on table a without me rerunning update statistics. So I don't think update statistics is really involved.It appears to be intermittent. Any ideas? Thanks, Dianne