Keith's note: A note titled "NASA Reccomends Discontinuation of Student Rocket Activity" went out to NASA's education mailing lists this afternoon with some urgency. No other detail has been provided by NASA.
"Recently, an air pressurized paper rocket launcher being used by an educator failed. This launcher is described in NASA's Rockets Educator Guide, publications EG-2011-11-223-KSC, pp. 86-90 and EG-2008-05-060-KSC, pp. 86-90. NASA completed an engineering investigation into the failure and determined that the launcher, or design equivalents, should not be used. NASA has removed the launcher design from its website and its education curriculum. Individuals and organizations should immediately discontinue use of the launcher published in the referenced NASA publications. The point of contact for additional information is James Stofan, Deputy Associate Administrator for Education Integration at email@example.com. We request that your organization assist NASA in disseminating this information as widely as possible throughout the education community."
If there is some inherent danger then this is a prudent thing to do. This is the document that NASA has taken offline. It took me 10 seconds to find it. They have managed to scrub it off of NASA's website but similar technology is easily available online via a simple Google search: