Just to be sure, how do you know it is rights enabled (it would give you a message if it was when you open it)? Also, in the station next to you, are you sure it's actually being opened by Reader?
Barring it not actually being enabled, transfer the file from that station to yours to be sure the file you have isn't corrupted and give it a shot. If it works on one, it should work on all the others running 7.5 and higher.
If none of that works, is it a file that you can post here in public so we can take a look at it?