The client version is 4.91 SP2

I am trying to get an unattened install of this version and keep running
into one problem which I cannot find a single source of information on.
I have configured an unattend.txt file and ACU.ini. Now the install goes
along quite smoothly till just after all the files have been copied over
to a workstation from my designated server. Then a prompt pops up asking
whether or not to install the upgrade. I have tried ask far as I can see,
everything possible. So if someone has a fix or links to any source of
info I would be most grateful.