I thought this was just happening to me! I just decided to check my stats over the last few days for a campaign on Y and have realised that in the last week or so, not a single ad group within that campaign has been profitable and yet a few weeks ago these same ad groups were converting well. I have now paused the entire campaign and will consider what to do next. G and MSN remain remain profitable at this time. Seems like Y have screwed up big time, and they have had the audacity to increase minimum bids considerably on some keywords just lately!