Okay, gents, problem solved. But what an odyssey this was...
Here's a step-by-step account of what happened and how it was resolved:
(1) Whenever I tried to save my project, it would hang at the at the 20% point of the "Saving Chapter Thumbnails" window
(a) This hang would only occur during saves, and occurred for both manual and autosaves
(b) This hang would also occur if I opened up an earlier iteration of the project and tried to save it
(c) No matter how many files I removed from my project, as long as there was one original file remaining, it would hang when attempting to save
(d) I could successfully save if I deleted all media content (as well as if I added content back)
(e) A complete uninstall/reinstall made no difference[/list]
(2) I noticed that most of my project media files were missing from the library pane. The fact that they were missing
appeared to have no effect on the project, i.e., I could play and edit the files in the timeline normally. Via the properties option, I also confirmed that the path to the actual file was valid in each case.
(3) I reimported all the missing media files back into the library. Curiously, none of the thumbnails had the green check mark in the corner to indicate they had been added to the project even though they were in fact already included in the project
(4) I appended all the restored media files from the library into the project timeline, such that there were two copies of each of these files in the project, the original modified (panning, placement, corrections, etc.) versions and the newly re-added versions at the end of the project. The green check marks for the corresponding thumbnails in the library pane were restored.
(5) I deleted all the newly added media files. The green check marks for all the subject media files remained! So now every file in my project existed in the library pane with a corresponding green check mark on the thumbnail, and my project was exactly as I intended it to be.
(6) I was able to successfully save!
(7) HOWEVER, after doing more editing on the project, the hang would occur again in precisely the same manner as before. To correct the problem, I would again have to reimport all media into the library, insert it into the project timeline, and then promptly delete it. This was a painful workaround, but it at least got me through the project enough to produce it and burn it.
But here's the kicker. I downloaded and installed Cyberlink's latest patch from a few days ago (i.e., 1129b). Since that time, the problem has gone away entirely. Which means that they either corrected this problem in the patch, or the act of patching, per se, replaced a corrupt program file.
Very strange. I sincerely appreciate your help in trying to resolve this issue.
Erin