I want to update you regarding this problem, that is solved, now. The solution was quite simple.
If you look at the System/Setup tab, there is one entry for Directory Service Connectors. Then, if you select Active Directory and Configurable LDAP options you will find user-id and password configuration (I erased the data from the image below to keep confidentiality). Well, in our case, the user-id had changed the password without updating it in QVS. After entering the new password, the processes run as usual.
Hope it helps. Regards,