One of our production databases had 25 constraints that were disabled. I would like to know how they became disabled. The server is a PIII with 2gb ram and 70 gb raid 5 running Oracle 8.1.6. Has anyone ever heard of 8.1.6 having problems with constraints becoming invalid? We are not running auditing. Does anyone have any suggestions as to how I can find out when they became disabled?

Any help would be appreciated. I certainly am not discounting the possibility that it was either done intentionally by a person or by the software that runs against the database. I just want to make sure that I check out the other possible causes as well.
Thanks.