Thank you for the replies, friends.
Shova --
I'm not certain if I ran the updater for the CEP (it's been about a month since actually being able to even open the module to work on it), but I know I did not delete bunches of custom content at a time. However, I've added various haks over time, and I have a strong feeling that this is where the problem happened, as I'll explain at the bottom.
Zwerkules --
I thank you for pointing that out, which I'll be on the lookout for in general as I build.
Jez_fr --
Thanks very much for the offer of help. The module itself uses a number of haks, all of which can be found online at (where else) the NWN Vault, although I did make a music hak of my own. I may take you up on your offer still, but here's what happened yesterday:
I tried opening the second-to-last save of the module, and it worked, even though it hadn't previously. See, I had played on the Cormanthor server a little over two months ago, and it required a bunch of haks to download. Finding that module to be quite beautiful in its design, I added some of the hak files to my own module, and I think that's where the trouble started. It seems the Cormanthor haks are combinations of the NWNCQ and such, and the server does not apparently say you need the CEP... long story short, I'm wondering if there was a conflict by adding both sets of haks. The second-to-last save of my module did NOT include the Cormanthor haks. And behold, it works.
Anyway, it seems that as of yesterday, I do have my module back, albeit unexpectedly and after it not working under the same conditions two months ago.
Thanks again, folks.