When I was testing with the new PowerCLI feature to work with multiple VIServers, I ran into a bug. Whenever you disconnect from a VIServer you can’t reconnect to that server. You can however connect to another VIServer, but never to the same VIServer again.
As a workaround for this problem close your PowerCLI session and start a new one or…
Specify a username and password when connecting
Connect-VIServer <servername> -user <username> -password <password>
So it looks like the problem is only related to using passthrough authentication.

on Nov 27th, 2009 at 3:51 pm
[...] When I was testing with this new feature I ran into a bug. Whenever you disconnect from a VIServer you cannot reconnect to that same server again. You can however connect to another VIServer, but never the same again. See my earlier blog post about this bug here. [...]
on Jan 26th, 2010 at 2:56 pm
Is there any official word on this? It’s really annoying when running scripts in say PowerGUI and having to restart the entire application to rerun the script. I refuse to specify a password and have it stored in cleartext
on Feb 1st, 2010 at 9:33 am
As far as I know it’s reported as a bug, so we have to wait for a new release. In the mean time you could use the New-VICredentialStoreItem and Get-VICredentialStoreItem cmdlets to store your username/password in a credentialfile instead of using clear text.