See case 291843 for more details, but basically if you put bad values in the snmp version 1 specific settings, change the version to be 2c, you can save successfully but you'll get errors when trying to emit snmp traps (even those version 1 settings shouldnt be used) and you won't be able to see whats wrong with your settings (because the version 1 settings are hidden).
This bug was previously known as http://jira.rhq-project.org/browse/RHQ-2398
Temporarily adding the keyword "SubBug" so we can be sure we have accounted for all the bugs. keyword: new = Tracking + FutureFeature + SubBug
making sure we're not missing any bugs in rhq_triage
in gwt, we do not have these settings in sys config - this is now part of the snmp server side plugin