Today I was trying to setup a Data Collector Set under performance monitor on a Windows 2012 system to monitor its disk activity. Once I had the Data Collector Set created and configured its schedule, I right-clicked on "Server Manager Performance Monitor" in the left pane and choose the "start" action.
When I did so an error message was shown saying: "when attempting to start the Data Collector Set the following system error occurred: The task is disabled".
It took some time to figure out what this message was referring to. At first I checked into the Services MMC, then I realized that the guilty object was the scheduled task named "Server Manager Performance Monitor" under "Task scheduler library / Microsoft / Windows / PLA".
I right clicked on it and choose "Enable". The problem went straight away and I was able to fire my data collection.
Hope this helps.