Thanks guys, I tried rebooting (several times), it is plugged into the computer (no hub) Formatting the internal memory via the reader doesn't do any good, there is nothing saved there for it to reformat. I thought about formatting via disk utility but I don't want to destroy my reader.
I have since figured out that the problem is with the computer, not the reader, I plugged it into my laptop (also a Mac) and it works great.