I have a three-month-old USB 2 CF card reader that lights up its LED whenever I insert a CF card, but then I get an error message that the "disk" is unreadable. I've tried two different CF cards from two different cameras. I can transfer photos off of either card via a direct camera connection, but not via the card reader. Everything worked fine yesterday. Is it safe to assume that my new CF card reader has suddenly croaked? Is there anything I should try to get it to work?