I believe this means that the system user ‘postgres’ doesn’t exist.
Launchd tries to launch PostgreSQL under that system user.
Did you perhaps copy over an PostgreSQL installation instead of using an installer ?
I actually did install Servoy 6 together with postgres (at the Camp). And did remove it again. My original prostgres installation is under /urs/local.
Last week my java installation did break and I updated to 1.6.0_29. Servoy was useless with this version. So I had to reinstall os and java. I thought, I might have lost a postgres configuration during these update processes? How can I create the user postgres without running postgres processes?