Server "hangs"

[NateDog]

I have two servers hosted at a datacenter on dual xeons with hyperthreading
and 4 gigs of RAM with ultra scsi hard drives.  I don't own these computers
of course that's just what the specs are basically.  They're running on an
OC192 backbone and all that good stuff - so I have tons of bandwidth and I
don't think the networking is causing this problem.  These servers are crazy
fast but sometimes the servers will "hang" then resume play.  But it's
really sparatic and it doesn't do it all the time.  And everyone will hang
at the same time and you get that green box with the arrow on it icon at the
bottom of the screen.  But then all of a sudden it "un-hangs" and continues.
Now I realize that there is a billion things that can cause server hangs but
that's not what I'm asking really.  What I want to know are maybe tips /
techniques / tricks to optimize the server to lower the chances of server
hangs etc etc.  Is there any cvars and such to use?  These servers are VPS
servers using virtuozzo if it matters.  So there are multiple servers on one
host machine.  But mine are the only ones running game servers.  If anyone
could give me some pointers for optimization I'd appreciate it.  I once
heard about zone and hung megs but not sure if that would help or not.
Thanks.

--
Nathan Peters