I have found a trend recently where SNMP on several Windows 2000 and 2003 (mostly 2003) servers stops responding to my Solarwinds apps. I can find nothing is the server event logs to indicate any errors. A lot of time this will happen right after some sort of outage at on of our branches. Once the branch comes back up their file server is showing up as unknown status. I have to log into the server and either restart the SNMP service or make a change to its config (comm name or add authorized IP etc). This seems to primarily happen at my branches which are connected to corporate via VPN tunnels. Any ideas why this would happen?