most all the 1.5s ive seen have the older thompson drive in them.
you might try to say upload the dash again, both xbox and evox or mxm whatever you plan on running. if that dont work try flashing the tsop with say x2 4981.06 , see if it helps ya any.
oh also , if its only freezing when there is media in the dvdrom drive, then try and boot the msdash and make sure the time is correct..