Intermittent network errors or NullPointer exceptions using IBM HTTP Server

Symptom

Network trace analysis will show that the expiration of the IHS keepalive corresponds to the following TRANSPORT_WSI_NETWORK_ERROR errors in the Content Engine error log:

2012-09-12T08:13:17.670Z 01543E84 WSI FNRCT0042E - ERROR CEWS Listener, unexpected exception (elapsed request time 60462 ms)
com.filenet.api.exception.EngineRuntimeException: FNRCT0042E: TRANSPORT_WSI_NETWORK_ERROR: A network error occurred when processing a Web service request or response. See the nested exception for specific details. See full stack trace for details. Message: Socket operation timed out before it could be completed
at com.filenet.apiimpl.wsi.serialization.Util.ereOrIoe_common(Util.java:676)
at com.filenet.apiimpl.wsi.serialization.TokenReaderNst.<init>(TokenReaderNst.java:94)
at com.filenet.apiimpl.wsi.ServiceSessionNst.sHandleIncomingRequest(ServiceSessionNst.java:914)
at com.filenet.engine.wsi.ListenerNst.service(ListenerNst.java:163)
...
Caused by: javax.xml.stream.XMLStreamException: java.net.SocketTimeoutException: Socket operation timed out before it could be completed
...
Caused by: java.net.SocketTimeoutException: Socket operation timed out before it could be completed
...

Or the following java.lang.NullPointerException:

2012-09-12T08:13:17.835Z 01543E84 WSI FNRCE0000E - ERROR CEWS Listener, problem sending response, first try (elapsed request time 60462 ms)
java.lang.NullPointerException
at com.ibm.wsspi.webcontainer.util.BufferedServletOutputStream.write(BufferedServletOutputStream.java:384)
at com.filenet.apiimpl.wsi.MtomOutputStream.write(MtomOutputStream.java:39)
at java.io.PrintStream.write(PrintStream.java:430)
...