CAPE CANAVERAL, Fla. — After getting a little free time Thursday, the last space shuttle crew was woken up to deal with a second computer failure on Atlantis. The astronauts switched to another of the five main computers on board, and NASA said the shuttle was in “stable condition with no concerns for the crew’s safety.” A computer had also failed on Sunday. The crew had gone to bed late Thursday afternoon, but Mission Control woke them up about 1½ hours later because of the failed computer.