"The exact cause of the problem is still unknown"

Here's a massive printing glitch, problems with paper feeds, that probably has happened to you.According to CNBC, U.S. government printing presses were unable to correctly feed new paper used to make $100 bills causing some notes to crease and create blank spaces on some of the bills. An unknown number of bills printed could be damaged so the entire batch of bills, 1.1 billion of them, will be unusable until someone figures out a way to sort the good ones from the bad. The exact cause of the problem is still unknown.


Above quote from zdnet which has nice pictures.