i ended up flipping the process over, because i wanted to make sure there was an endpoint; instead of slowly inserting the working system hive into the broken one, hoping for it to eventually work, i copied over the system hive used by the setup disc, which got around the security descriptors and let me figure out where the error is. i quickly figured out that the 7xb error is actually being caused by a broken service, although i haven't figured out which one, yet. just realizing what was happening was good enough. so, i copied the broken system hive back into the config directory and imported the services hive that i copied from the fresh install, which brought me up to that chkdsk i had scheduled (the disk is fine). the thing is booting, but to a generic set of services; at least i know i can salvage it, though. the next thing to do will be to copy each service back into the registry until the blue screen comes back, fix the problem, and reimage the drive with the corruption reversed. the install should be exactly as i left it....
a corrupt service or driver shouldn't cause this kind of mess; windows is supposed to hold your last working configuration, but the error seems to have ended up in both control sets. very strange. but, the important thing is that i can salvage this.