Treasury Secretary Henry M. Paulson, Jr. urged leaders of all African nations receiving U.S. aid to 'hold off' on cashing their humanitarian aid checks until after April 17, when the U.S. government is expecting 'a whole bunch of money to come in' from 2006 tax returns. 'I know the checks we sent are dated for the 11th, and I'm pretty sure they'll clear anyway, but to be on the safe side, please wait until the 19th or 20th,' said Paulson on Tuesday, adding that the U.S. is experiencing an 'extremely minor' cash flow problem at present. 'The Rand Corporation told us they would hold our check for $7.8 billion until the end of the month, so unless they're being dicks about that, all this probably isn't even a big deal. But you never know.' Paulson added that the Treasury Department 'was as caught off guard as anyone' by the fact that tax day is not on April 15 this year. 