Per this thread: Universal Device Poller: Browsing MIB tree results in "Object reference not set to an instance of an object." , devices being removed from NPM can cause errors / alerts when they have pollers assigned them, and when the pollers are not removed prior to the device(s) being removed.
Although the database cleanup job appears to correct the problem retroactively, wouldn't it be best if NPM automatically removed pollers assigned to devices being removed, thus eliminating the errors and the multiple times we've seen "Object reference not set to an instance of an object?"
As an additional helpful request, that message isn't as intuitive as it might be. Seeing "Object reference not set to an instance of an object" creates confusion and Thwack and Support tickets.
When an alert like this one shows up, how about adjusting it to include some different information, and include hot link(s) to explanations of the alarm? Obviously the links need to go to places that not only explain the error, but that also provide steps to remediate or troubleshoot it.
