Are you binding the app server to a specific address (i.e., staring it using the -b option?)
Not that I can determine. I'm running with the following:
JAVA_OPTS="-server -Xms256m -Xmx1536m -XX:MaxPermSize=256m -Dsun.rmi.dgc.clie
Next question - what do you mean by "JBoss would not run on the machine any longer"?
Jboss would start on the server reboot, but would soon shut down with no logs or other notice as to why it suddenly stopped. A 'ps aux' would show the java was no longer processing.
The curious part is by changing IPs back, it has remained up and stable. That's why I am associating it with the IP change causing the issue.
I suggest you try starting it from the command line - then you can see the console output and any errors that might have appeared. I am rather surprised, though, that neither the server/xxx/log/boot.log or server.log contains any error indication.