We have a custom performance counter setup that is giving us daily false alerts from it's speed trigger.
The sensor is set up to scan the performance counter every 30 seconds. We just want alerts if it sits at 0 for a certain amount of time (we have it set to 30 minutes at the moment). This indicates to us that the service it is attached to isn't working properly.
When we receive a notification that the speed trigger conditions have been met, we log in to the PRTG server and check the live data. From the live data we can see that the counter is not at 0, and isn't at 0#/s and hasn't been during the last 30 minutes. This happens daily but we haven't been able to determine the cause yet.