Make sure that the "Settings/User Preferences" are pointing to the right location in your QlikView Desktop:
If the Default License Lease Server (URL) is pointing correctly (obiously not to localhost for your users ...) then the QlikView Desktop will try to touch the server every-time you start the desktop to renew it's lease. No need to do a
file open in server manually.
However - I don't know how your LDAP is integrated with your Windows computers ... so maybe this will not work automatically in that case you can do a file open in server anyway but select ALTERNATE IDENTITY like this:
The benefit of setting both the LOCATIONS for QlikView Management Console (URL) and QlikView Server AccessPoint (URL) in User Preferences is that you will get these extra menu options on your TOOLS menu: