This thread is driving me bonkers

.
It brought to mind a book I read about a computerised building that goes berserk, and starts killing the people it has trapped inside.
All credibility was lost when a couple of characters got slaughtered by the overnight washroom cleaning routine

.
But I can't for the life of me remember the name or author - I think it was their second novel, and I'd enjoyed the first.
I'll be up all night now trying to remember what it was.
Phew, Google to the rescue (finally)! It was 'The Grid' (aka 'Gridiron') by Philip Kerr.