Please make it configurable whether the failure of a performance counter (like "Error occured while trying to get value for counter % Processor Time [_Total] [localhost]. Disable counter.") posts a warning (currently the only way) or just a message into the log. While this is definitely much better than posting an error, it still costs time to look into the log only to find out that the counters are disabled, which may be not really important at every single test run...
And maybe you can also correct the typo in "occured" ;-)