A few bigapps,including VolanoTest, atg and tomcat, throws NullPointerException intermittenly.
For tomcat and atg, test still goes on even with the NullPointerException.
On the other hand, when NullPointerException happens, the client of volanotest hangs.
Here is the stack trace from tomcat log:
run.tomcat Latency = java.lang.NullPointerException
        at java.net.InetAddress.getAllByName0(InetAddress.java:1136)
        at java.net.InetAddress.getAllByName0(InetAddress.java:1098)
        at java.net.InetAddress.getAllByName(InetAddress.java:1061)
        at java.net.InetAddress.getByName(InetAddress.java:958)
        at java.net.InetSocketAddress.<init>(InetSocketAddress.java:124)
        at java.net.Socket.<init>(Socket.java:178)
        at atg.core.net.HTTPConnection.openSocket(HTTPConnection.java:274)
        at atg.core.net.TestHTTPConnection.connectWithError(TestHTTPConnection.java:67)
        at atg.core.net.TestHTTPConnection.getInputStream(TestHTTPConnection.java:96)

In volanotest log, "Unexpected error for Test2 in Room10 (java.lang.NullPointerException)"
is the only error message I got. I am guessing that the cause of NullPointerException encountered in volanotest is the same as that of NullPointerException from atg and tomcat.

Test config info:
1. App name: VolanoTest
java version: Java HotSpot(TM) 64-Bit Server VM (build 1.6.0-ea-b45, mixed mode)
VM flags: -d64 -XX:+UseParallelGC -XX:CompileThreshold=100
Test machine: jtg-sunfire-3.sfbay
# uname -a
SunOS jtg-sunfire-3 5.10 Generic_Patch i86pc i386 i86pc GNU/Linux
The first time NullPointerException happens after 3 hours, the second time after about 20 hours.

2. Name: Tomcat
Machine: jtg-emt-4
# uname -a
Linux jtg-emt-4 2.6.5-SLES9_SP1_BRANCH_2004121317250991-smp #1 SMP Mon Dec 13 17:25:09 UTC 2004 x86_64 x86_64 x86_64 GNU/Linux
java version: Java HotSpot(TM) 64-Bit Server VM (build 1.6.0-ea-b45, mixed mode)
VM flags: -server -XX:+UseParallelGC
NullPointerException happened 28 times in 5 days.