I just tried three times to book a flight using my opera browser on the BA website.
i got all the way through to the end, when i get a message (after entering my cc details) that the BA systems are down and the booking cannot be completed.
i then used IE and it worked!
i'm pretty sure the systems were not down but somehow they didn't work with opera, but they couldn't tell me that, they just gave a generic error message.
rant, rant, rant ... if another flight had suited me i would have gone elsewhere, sadly i wanted that one!