Thanks everyone for the answers.
The problem is that I tried both FreeBSD 9.* and 10.* on many DL360 G3 (just to be sure that no hardware fault was involved).
The last working version, for that specific machine, seems to be FreeBSD 8.4 (which is the one that I'm currently running).
I don't think the responsible would be the new installer, because the machine gets stuck during the *boot* process (the installer would come up later...).
I even tried to disable the "Virtual install disk" from BIOS and the USB controller, but the problem persists.
As a further test, I prepared a DL360 G3 with FreeBSD 8.4, then upgraded it to version 9.* (instead of trying to install 9.* directly from CD). When I rebooted the machine, the problem came up again...
So, I suppose the problem is in the kernel that comes with FreeBSD >= 9.*, that for some strange reason does not support that specific hardware anymore.
I know the existence of the HARDWARE NOTES, but they are not accurate enough...