It has been a horrible half for Ireland. An Injury to Johnny Sexton have them up against it, and it looks like Paul O'Connell could be dealing with a serious hamstring injury.
Just before half time, O'Connell was poaching at a ruck. The French players came in to clean him out, an O'Connell's hamstrings were stretched beyond what they should.
The signals from the physios seem to hint that he won't carry on, and looking at the footage it's not hard to see why. There is a chance that he could shake it off at half-time, but I wouldn't be confident.