BM3.7SP2 / NW6SP3 w/ 500MB RAM

Our BM server became suddenly slow today. When I checked the current
activity for the BM fast cache 533 connections were open. 243 on the
side and 292 on the server side. And the numbers were slowly growing.
average I only have about 40-50 client side connections at one time.
Utilization was at 100% as well. I went to run monitor on the server
but it
just hung so I couldn't check the traffic on the NIC's nor could I get
thru remote manager to check things out. BM alerted me with this
"The system is short on event control blocks and network I/O may
degrade or
fail". I just bounced the server and everything is ok for now. I
checked for
abends...none and nothing of concern in the sys$log.err. The remote
health was showing the server processes being low though.
I started thinking memory, but it looks like the open connections are
being torn down.
Any ideas?