Stumbled across this fantastic Greenmachine MP created by Cameron Fuller and had to post about it on this blog.
The origin webpage is:-
Basically the MP utilises the greenmachine tool and adds tasks to your SCOM console so you can reset the health of monitors (regardless of state) including rollups (R2 only) for indivdual computers or groups. This is very handy for cleaning up your SCOM console when you have the scenario whereby lots of monitors have been closed without having their health reset.
The files you require including the greenmachine tool and instructions on how to install and use the MP are available from here:-
I have tested this in my environment and it works a treat.
NOTE:-The instructions say that you can’t do a multi-select on the Computer View just in case you miss this part but you can reset health on multiple machines simultaneously using the Group View.