Has NFactor just gone up or something???

I've been mining for days at 1.2mh/s absolutely fine. But noticed that at some point this morning my hashrate had halved and that I was now getting lots of HW errors.

I've had to drop the intensity from 13 to 12 to stop the HW errors.

I know it's not a hardware fault as other coins mine absolutely fine with the settings I've always used.