Just stick a wooden toothpick into the 3.3 pin and break off flush.
That is a problem with the older arduino boards that used the FTDI's internal 3.3vdc regulator to supply that shield pin, as it has like a 50ma current limit and seems to have no self protection from overcurrent draw.
The current Uno board has a on-board 3.3 voltage regulator which makes it less likely to cause problems as the regulator will shutdown if too much current is attempted to be drawn from it.
Lefty