hi, I upgraded to El Cap from Yosemite. I now need to restore back to Yosemite. I'm trying this by booting into the recovery partition and restoring from a time machine back up. I've already done this a few weeks ago and it worked perfectly. It isn't working this time. When I reboot after restoring, the progress bar gets stuck. Tried booting in safe mode to no avail. Tried resetting pram but no good. Any ideas? I can boot off of another disk and my restored boot disk looks fine: all files seem to be there in their correct places. Really stuck with this. any help appeciated. Thanks.