Ok,
I had a case open with GTAC (01818159). They found the root of the problem. They confirmed it is a bug that affects NMS-BASE license users and will be fixed in an update at the end of the month. As a workaround we installed NMS-ADV eval license.
Well, we had applied to 8.2 beta test but not accepted at that time Not all mortals has NMS-ADV license. It was very frustrating for us, XMC were kicking us out to login screen every two minutes, even if you were actively using it.
Regards,
Rahman