I LOVE, LOVE, LOVE to cut blocks down. I've sewed for many years and still have problems with everything coming out perfectly, so this whole 'cutting down' movement is perfect for me! But if I am doing this and every block has to have a certain design feature, say a point intersection, at exactly the same place, I will put a bit of tape or some other visual clue on the ruler to be sure I cut all the pieces the same. I use Deb Tucker's rulers a lot, because not only is it a cut down procedure, but she has the lines on the ruler that need to one up with the square when you cut it down. To your current problem, like many have said, bag up the pieces and set them aside for a while so you can come back to them fresh, and not discouraged. They're not going anywhere, you don't have to feed them, so give it a rest, and move on to something else for a while. Good luck, and please don't be discouraged - this sort of thing has happened to all of us!