Been bashing my head on the keyboard for two days on this, finally coming for help. So, we have two pollers - a primary and a secondary - that polls our database. We had this database fail, so we went into the Configuration Wizard on each poller and ran it for our back-up database. Here's the part where it gets screwy.
All the sites that are running on our secondary poller are showing traffic, going down, etc. - essentially acting normal - on the Network Perfomance Monitor webpage. The primary poller, however, isn't showing us any information. All the services are running. We've stopped and started the services, all to no avail.
Issue is resolved. Just for the record, we shut down all services on the troubled poller and waited until the netstat wasn't showing any further connections to the downed DB. Shortly thereafter, we turned everything back up and the webpage started updating.
The assumption is that the poller was looking in the wrong place, or was waiting on information from a DB that was down.