At the point where you use the VDU in NCR for the second time, and turn in 12,000caps worth of coins, if you close out of the conversation at a certain point, it breaks the computer usage and cannot be used further it would seem.
-Had all of the coins in my inventory
-Got to the point where it prompts putting the coins into the machine
-closed the window before proceeding
-no coins in my inventory now
-interacting with the machine does not bring up the equivalent chat window, but rather a green text in world over the machine saying "This appears to be a fully functional vault-tek videocom" and can't interact further
-quest still shows "I will have to return to the videocom, and accept those hefty fees"
A little irksome the bug took the coins even before I "accepted the charges"