I had a rather strange issue today.  All playback through FFUC was being slowed down on my windows box.  Everything played fine in OSX.  Neither reboot of a PC, nor restarts of FFUC helped.  The solution that finally worked was to switch Sample rate from 48Khz to 192Khz.  This immediately fixed playback speed and after switching back to 48Khz it was still good.  Maybe this will help someone.