What exactly happened to the frequency? Does the the d2 firmware clocks down, but the d1 firmware runs stable?
If yes, it is a clock stability problem (too much jitter). I saw that earlier and thought it would have been fixed because it does not appear anymore on my 1.15d FPGA board test cluster. I will change a few parameters and post a test release next week (because I cannot reproduce this problem here).
If that problem appears, just use the d1 firmware (from the new release). It is as fast.