How do I reimport iPhoto Library from an external hd?

Question

Hi all - apologies if this has been posted before (but, couldn't find exactly what I need in the forums). I think I need to rebuild/erase, whathaveyou, my current iPhoto Library on my Mac because I'm getting a perpetual error/alert:
*"The Volume for "CDY_.0005.JPG" cannot be found. Insert the disk or*
*connect to the server volume and wait for it to appear on the desktop,*
*then try again."*
*Here's what happened:* I originally downloaded some pictures and video clips off of Compact Flash memory cards into a new folder ('Photos') onto the desktop of an IBM Thinkpad. I then transferred that folder - 'Photos' - to a new external hard drive (250 GB, Western Digital MyBook Essential Edition). They are visible on the external. I then tried to tranfer this 'Photos' folder from the MyBook into my iPhoto Library by going to 'Import to Library' and then choosing the appropriate drive (i.e, my external MyBook). This folder and it's contents (i.e, the images and their respective folder in which they were placed) seemingly went into my iPhoto Library, and also seemed to organize themselves appropriately....what I mean by this is:
All of these images/videos I'm talking about are for my grad project, and must be organized by date. I had one scouting camera at each of 26 different sites. Each of these sites has it's own folder....and each of folder (site) contains an album for each date the site was checked. So in other words, I've got LOADS of albums organized by date checked and site. *+I must preserve this structure or data analysis and, subsequently, my thesis, will be quite painful, cruel and unusual punishment!+*
*By the way, I have tons of images and videos named "CDY_.0005.JPG" because of the way the scouting cameras save files to the memory card. Each time the card is cleared (each date I checked a site and downloaded images on a card), images are again saved numerically:
CDY.0001.JPG.....CDY.0002.JPG etc etc. Also, these cameras were set up to take motion-activated video (they're infrared), and for every video it captures, it takes a still photo. So, every still photo is essentially associated with a video, and vice versa.
This error/alert occurs when I try to view images that were transferred from the IBM/MyBook to iPhoto. Additionally, since I did the transfer, another qwerky thing occurs: Regardless of what I'm trying to do in iPhoto, when I open iPhoto and click *anywhere else* outside of the iPhoto window (such as back to the desktop or click to open any other program) I get this exact same alert, but it's always an .avi file, not a .jpg, and in this alert (.avi), I am forced to force-quit iPhoto because if I hit cancel, the pinwheel appears indefinitely and never goes away, at which time I forequit and see 'iPhoto (not responding). Essentially rendering iPhoto useless for my purposes (I've got to be able to go back and forth between Excel and iPhoto, for example, and cannot do so because of this alert).
So, I feel like to I need to start from scratch to fix this problem (through a series of discussions with Apple reps and the Mac gurus, I was told this is probably due to corrupted files, I may need to rewrite the program etc etc). And...so...the real QUESTIONS:
*Is this really the solution (backing up my iPhoto Library to the external, which I've done, then clearing my current iPhoto Library on my Mac entirely, then reimporting)?? I don't really have much time to fiddle with too many different solutions...if re-creating a new library seems extreme, I guess I really don't care, as long as it works.*
*If I do this, and delete/clear all the photos in my iPhoto Library on the Mac, then reimport them from my MyBook external harddrive, will they be imported in the same structure as they were before I deleted them from iPhoto? Will I still have all photos in the same albums under the same folders? It is essential for me to retain this structure, as I am analyzing images/videos for my grad project and all these images are organized very specifically by certain dates. *Is it possible to do this??** I was told that if I burned my Library, or folders, onto a DVD, and then brought them back into iPhoto, this would retain the folder structure. True??
Thankyouthankyouthankyou in advance if anyone has some thoughts! I'm still relatively new to Macs, so rudimentary, kindergarten step-by-step thoughts are encouraged....Cheers!

Answer 1

TD-
Great, thanks for helping. I think I've got some useful info for you. I went throught the process you suggested, here's what I found out:
I viewed the rolls through the Pictures/iPhoto Library/Originals route. I see the rolls, but I do NOT think these images from the pc are there. Here's what's weird: Towards the end of my 'rolls' list (they're not named, just numbered), the rolls jump from 495 to 503. Though I didn't check all those rolls up to 495 (it would take forever!), I'm pretty sure those are my 'ok' files/rolls. I don't think they house any of the pix I was having issues with (the ones that came over from the pc). BUT...roll 503 DOES in fact have one image, and here's what happens when I click on it:
Only that jpg icon shows up where the picture normally would be viewed, it has a shortcut arrow in the bottom left corner (like that which would appear on any shortcut icon on your desktop), and the info for this image is different than the other ones:
Kind: Alias
Size: 4 kb on disk (usually these scouting camera images are upwards of 800 or 900 some kb)
Created: 9-23-07
Last opened: fetching...
And finally, the infamous alert comes up for this specific image: "The volume for bla bla bla cannot be found...." etc etc.
I'm pretty confident that the missing rolls that should be after 495 are from when I tried to transfer the folders of images from the IBM because those are the very last things I 'imported' into iPhoto. Thoughts??? One other weird thing I noticed, too, was some of my rolls do NOT show all of the images that are in the iPhoto folders...in other words, say roll 300 shows 4 images in the 'Originals' folder you asked me to go to. Well, each roll was created when I would download each card, so essentially I know that each roll represents each time a card was downloaded. But, when I go straight into iPhoto and look in that folder that represents when I downloaded each card, there are many more images there than are in the 'roll' folder for the same download...yikes, does that make sense?!
Thanks again...I feel we're getting somewhere at least!