Beware of a strange Flash Builder behavior: when network monitor is activated in the IDE, Flash Builder will automatically add an include-libraries entry in the compiler configuration passed to MXMLC for netmon.swc (you can see it telling MXMLC to dump the configuration). I noticed that this may actually overwrite the <include-libraries> declared in the source <App>-config.xml file, creating problems at runtime if your project requires them.
Just spent some hours trying to debug this issue, I hope to save this time to others and to my future self :)
