Forum OpenACS Q&A: Response to file size limit when su'ing
I would check for any really huge files on the machine, and for any ulimit limits that seem unusually low (ulimit -a will display them, so you can compare values when under X vs in a text mode console).
I'd also check the log files especially /var/log/messages for more precise error messages that may be relevant.
As a point of reference, I don't see this on my RH 7.1 boxes that have OpenACS 3.2.5 on them.
Is it only the postgres user that is affected, eg can you do
OK (assuming you have a user account named brad)?