first of all, go to the usual places (XBINS) and download krayzie's UXE installer. it's much better than SID.
also, all versions of SC (AFAIK) are exploitable. it never got patched for some reason.
it could be that the action replay is corrupting the save. larger saves tend to get corrupted more. when you go to xbins, download the SC with EVOX save. it's a very basic save without an installer that you may be able to get onto the card without corrupting it. if you can run that, you can get FTP access to your xbox. once you have that, you can put the memory card into one of the controllers, FTP in, find the drive with the controller (it will be something like H-O) and delete the save on there and then copy krayzie's save over to it. that way, it will be the xbox writing to the memory card via the FTP client and therefore it should not get corrupted. now go into the MSDash, delete the save (btw, you should delete all saves from that game before trying to load an exploited one or else it won't work) and copy over the one you just put on the memory card.
