Moments before the planes crashed into the WTC, unknown parties sent in computer instructions for massive financial transfers. The computers recording those transactions were destroyed in the collapse, erasing the records. In effect,someone had "borrowed" millions of dollars, then erased the bill. Then a company in Germany, using a new laser technique, started reading the drives recovered frm the WTC, to find out just who had had this advance knowledge of the 9-11 attacks.
Then something mysterious happened. The company was purchased, and the project to read the recovered drives was halted.
http://archives.cnn.com/2001/TECH/industry/12/20/wtc.harddrives.idg/