JDBC: IO Exception Descriptor is not a socket

I get the following exception

   java.sql.SQLException: IOException descriptor is not a socket. Socket write error

using JDBC against an Oracle 817 database. I get successful connections half a dozen times then this every time until I restart the app server.

The JDBC is running in Allaire JRun on a Windows 2000 server against 817 on Redhat Linux 7.1. Database connectivity is handled through a hand written connection pooling mechanism and I saw a message on the OTN discussion forums which mentioned another message which described problems with this, but I can't find the other message.

Any ideas?

-- 
Jim Smith
Because of their persistent net abuse, I ignore mail from
these domains (among others) .yahoo.com .hotmail.com .kr .cn .tw
For an explanation see <http://www.jimsmith.demon.co.uk/spam/spam.html>