You say you formatted the card and replaced the files. What exactly did you do? I'm wondering if you had previously copied all the files, and then just copied those to the card after you formatted it. If so, you may have copied corrupted file(s) back to the card.
Or, even if you didn't do it that way, you still may have copied corrupted files to the card.
I would delete everything, even hidden files, and see if the card works. Or, re-format the card again from the blackberry, test, and then add a few files at a time and test.