if you are on GB firmware and ICS software,or vice versa,then that is indeed your issue.
have you just s-offed? if so, i would strongly recomend to run a full ruu and get yourself on ICS firmware. prior to installing a custom recovery, use the clear storage option in hboot.
after that finished,you can install recovery,install a rom.
you can get things onto your sd by:
1)card reader in the pc
2)enable usb storage in recovery