Due to the current shutdown of the US government, the NASA web sites are completely offline. For Pic-a-POD, this means that the Astronomy and Earth Observatory PODs are unavailable.
Pic-a-POD for iOS will continue showing some info about the last pics available (1st October) but will be unable to download the images.
Pic-a-POD for Mac is in more trouble as it tries more actively to fill in the blanks. With entire domain names off the net, this can take a very long time. So I suggest turning off Astronomy & Earth Observatory in the Sources menu until the government shutdown is over.