Thanks for that, I 've gone through this KB before without luck. This time though I am seeing this error in the vpxd.log
[08504 error 'Default' opID=SWI-f9a6658a] Failed to get a table to insert raw stats. Perf data will be lost
Which I found in this kb http://kb.vmware.com/selfservice/microsites/search.do?language=en_US&cmd=displayKC&externalId=2011523 that it should be solved in vCenter 5 u1 which is the one we are on.