theres a number of post with similar problems to yours. often its the case of the ds firecard has developed a fault. few things you can try, try connect to a different computer? try reformat the firecard (by the NDS, NOT by the pc), WARNING : all data will be lost. this thread http://forums.afterdawn.com/thread_view.cfm/637847 explain how to format. hope this helps. good luck.
