False reboot alert for Cisco appliance server in console. please advise.

Hi,

   we are monitoring the Cisco appliance server in solarwinds console with SNMP polling method. every two days we have received reboot false alert in console but we checked the server logs not available (no reboot events). how to fix this problem. please advise 

NPM-12.5 

snmpv2 Version.

Regards,

Krish.