When I turned on the tv on Sunday morning to watch NASA-TV, they were talking about a computer failure on two of the three. I thought there were six shuttle computers...
Five, actually - 4 running the primary flight software and cross checking each other. The fifth is running the Backup Flight Software; sometimes you'll hear CAPCOM mention BFS as it sometimes does minor functions to offload the other 4. Each computer is officially a General Purpose Computer (GPC).
...but they were talking about a Command and Control Multiplexor on the ISS that switched to places between the primary, secondary and backup computers.
It was one of those "Ah $?&*!" moments.
Yes, that it was. It started just after shift handover and (thankfully?) I was in the parking lot putting the van in reverse to go home after 13 hours on console. By the time I came back in 12 hours later, it was all cleaned up. Crew and flight control teams across the world did a great job!