I had a problem like this...as I recall, and it has been a while, the air stash didn't like the way I had formatted the card. It would work fine if I put the card in the slot and plugged the usb port into a usb on my PC, in that I could use the card. But The air stash would just turn off as soon as I turned it on when trying to use the wifi. That card must be formated a certain way (sorry, the details are vague). I think I was trying to use NTFS, but it wants FAT32. I wanted NTFS so I could save files larger than 4GB to it.
That's all I have to offer you.