Almost done with putting in all the drywall screen but enountered a problem with one board. Need about 4 more screws but so far when screwing in on one side, the wallboard started cracking/crushing the wallboard.

What would be causing this? The framing a tad off? How best in the future (if we ever do anything) to prevent this?

Also we may have a space that's really perplexing. Two butts come together and there is a visable difference in the way they come together. The lower piece I had problems screwing in as if I hit something, possibly a knot. I was finally able to get the third one it but it still protrudes (1/32 - 1/16). No chance for a nail etc on the other side.

Being that it's at the 8' level of a closet, we may just try to smooth it out with mudding or would you take out 3 pieces to see what is going on?

We've wallboarded so many times before with no problems. We are using the lighter weight wallboard but I can't see that as being a problem in the latter issue.