IHAC who installed OnCommand Core 5.2 on Scientific Linux 6.2 (based on RHEL), and after installation the dfmmonitor and eventd services stop. Looking at the logs, the eventd service reports it was unable to find listen on a port 49152 - ... Dfmmonitor looks like it stops when it can't communicate with eventd.
I recommend having them move to a supported version of Linux prior to opening a support case as that will be the first requirement should one be opened.
What you describe sounds like a port conflict so I would suggest looking for other applications running on the server (none should be). You should also ensure that SE Linux has been disabled or placed in permissive mode as per the DFM install documentation although this normally prevent installations.