The 'problem retrieving fairness data' is currently normal - it happens on our VC servers, too. For some reason, although the VC can report this fairness data, and the counter exists in the object definition, it does not appear to be presented when the retrieval is run. I'm looking into this; however the other CPU and Memory checks work fine so lack of Fairness data is not a big issue.
The 'fairness data' is the per-ESX host indicator of what percentage of guest resources requested are actually provided. In a low-usage farm this would normally always be >95% - its the lower of the two DRS graphs. If you don't have DRS enabled, of course, you probably dont have this figure available
I'm currently working to get a persistent session established with this - the performance of the VI API sucks and with a lot of servers it puts an unacceptable load of login/logout on the VC.