On installing the software you're prompted by the UI to start a oracle repository(for 9R2) with hte name oemrep including database et al). Having done that you're db & oms starts up automatically but since you can't customize that db(i mean redo logs are 100m each.. not so handy always) you're temepted(i was) to delete the db and recreate a customized db with a repository and there you might get the issue of dependency.

I'd suggest drop and recreate the repository. if not you'd want to recreate the db all over again...