Hi Cato-L,
What was the method of your installation? If SCCM, what was the command line that you used to install Acrobat on the client machines? Is the issue also reproducible when you install the customized package manually on a machine rather than pushing it?
Another question, what was the locale of the serial number? was it Norwegian or English? i'm assuming that it was a volume serial number not a retail serial number since you were able to grant offline exception.