I'm a FreeBSD server with several gigs of RAM. When I try to run two Paintball servers simultaneously with nohup and &, the first one usually (though not always) dies right as I start the second instance (which dies too). Strangely though, the two instances still appear under ps -a under root. I have to kill them with root in order to try again, because the ports are still taken up apparently.
Also, another oddity, attempting to redirect the output of the server doesn't work. The log stops being written too after a minute or too, and sometimes it's cut off (a line isn't complete). It used to work when I ran the server on Linux at the The Planet, but those days are gone.