Image issue

I'm running 10.5.8

Just recently, iPhoto started acting odd. When scrolling through photos, some just wouldn't come up. I can see the thumbnail, but I cannot access the actual photo at all. I did look at iPhoto's package contents to import the original into the library, and not only does that NOT work, but I don't even see a thumbnail from there. So I cleared the library, rebuilt it (opening iPhoto while holding down Command + Option), but it's still happening.

So I thought maybe it's my camera, so instead of letting iPhoto import everything, I plug in my camera and manually move photos into Iphoto. Some photos still "disappear" it's just less frequent (1 of 5 being bad, versus 4 of 5).

Now screen shots are acting up! I wanted to share some travel photos, and due to my new found paranoia, I left the originals in my external (where I have been backing up my irreplaceable photos for the last 3 years), expanded the photo, and saved the screen shot. Now, just a few days later, either the screenshot is half black if visible at all.

So for now, i'm keeping all of the photos in my camera after my attempts to import. Seems that the problem is with the computer itself, but I really have no idea where to start!

Again, OSX 10.5.8, on a seemingly ancient first gen Macbook. I can't afford a new Macbook right now, otherwise i'd happily upgrade to the fancy new billet book! I have installed the latest updates, and repaired permissions.