Client is not authenticated to VMware Inventory Service - http://localhost:10080/invsvc

I have a newly setup vCenter 6, integrated with our AD ( using integrated Windows authentication )

It was working ok for a while, I rebooted the server today, all a sudden I am getting

"Client is not authenticated to VMware Inventory Service - http://localhost:10080/invsvc" when login as domainuser\myaccount.

If I login as vsphere.local\administrator, then everything is working as supposed.

Finally I had to remove the AD ID source, then re-add it back, then it's normal again.

Any one see similar problem?

Another problem ( might be related ) is when I add the AD as ID source, sometime I got

"The vCenter Single Sign-On service is not currently joined to any domain. You cannot complete the current operation."

but most time it's ok.