bschmeltz
Contributor
Contributor

I was also having this problem and after much research it appears that this is a very wide spread sporadic issue and it isn't always the same cause.  What I have found is you may also get this same error on Windows 7 using client 5.1 and it is being caused by the UAC, so you can either turn UAC off (if allowed by your company policy) or you can "run as administrator" everytime you need to launch vSphere.  Hope this helps.