Hi - so this is R10.2.1 - and a DSS install covering multiple Landscapes - and this one SpectroSERVER is in trouble. I expect you can try to model one of the problematic devices (or are all device problematic?) - onto an other SpectroSERVER/landscape to verify the SNMP agent itself is totally fine (which the poll already points to).
So - next then is - once the SpectroSERVER is restarted - if that symptom persists?
Next then is - to check into $SPECROOT/Install-Tools/.history file - if there are patches already installed.
Finally - is that device (or these devices) are monitored by SNMPv3 setup?
It appears there are some massive SNMPv3 issues for which corrections already exists - but in case this is not SNMPv3 then there are some fixes around SNMP-polling threading issues. cheers, Joerg