IPhoto 6.0.5 thumbnails and photos "lost" -- please help

Question

I have a large iPhoto library (17,000+ photos), located on an external bus-powered Firewire drive. I'm using iPhoto 6.0.5. The portable drive accidently disconnected. After reconnecting it, iPhoto still finds my library, still has all of my keywords, albums, and has the correct image counts in each. But ALL of my thumbnails are grey'd out, and clicking a thumbnail brings up a grey'd out photo with a question mark.
I've tried all of the rebuilding options available using CMD-OPTION. They all run quickly, and have no affect.
I've tried disk utility on the external drive -- no problems found. I've tried disk warrior on the drive, and it does rebuild a new directory, but gives me an error message preventing me from replacing the directory ("The new directory cannot replace the original directory due to a Mac OS services failure.")
The file structure looks fine on this iPhoto library, and I have done NO editing of it directly from the finder.
So I am sure all of the data is there. Can anyone tell me how to make iPhoto find these photos and thumbnails?
Yes, I do have a backup, but I had done some significant work in the library -- not to mention adding more photos -- since the backup, and would rather not lose the recent work.
Thanks much in advance!
PB G4 1.25GHz 2GB RAM   Mac OS X (10.4.8)  

Answer 1

Thanks for this reply. I did try what you suggested, and it was on its way to working, but eventually collapsed over the weight of my library size -- it hung up and was running very slowly at the end. For others who might try this -- I'm sure it would have worked, but it is a slow process.
I'm taking the liberty of copying a reply I received on another forum. This correctly identifies the root cause, and ended up being what I did, and it worked well and quickly, albeit I then had to manually import the photos since my last back-up. You might also be interested in his tool:
scrisp:
Unfortunately there's nothing you can do. The key component to the iPhoto database is the file titled "Library6.iPhoto". It was being written to when the crash occurred. There has been no way found to resurrect a library once that file has been damaged.
The best you can do is create a new library and import the Originals folder from the old one. This will give you the same rolls as the old library but some of the dates may be different.
To protect from this in the future you can make a backup of the database file. Then replace the bad file with the backup if you encounter the problem again. However, I recommend you backup that file after any import or extensive work within the library. Otherwise any work or imports after the last backup will not be recognized.
I've created an Automator application that will copy that file to your Pictures folder and give it an orange label. If you put the app in the dock you can easily backup numerous times a day. You can download the application, iPhoto dB File Backup, from Toad's Cellar
G5 Dual Core 2Ghz, 2G RAM, 250G HD, 250/200/160G FW HDs, 22" LCD, OS X 10.4.8, QT 7.1.3P