Ah, the thing which prints the flight strips and ties up the 4-digit (octal!) squawk code to the callsign went on the blink by the look of it.
That means you have to write your own flight strips (or get your friendly neighbourhood ATSA to do it for you) as the aircraft come into your airspace, and rather than it saying VIR046 next to the blip which is VS46, it will say something like 7652 (which you then manually match up to VIR046 by looking at the flight strips).
It slows things down quite a lot when this happens!
Cheers,
Mike