PowerPoint Pictures Do Not Appear In Right Window

I have downloaded 400 pics from a new 16Gb SanDisk memory in a Nikon D3100 DSLR camera to the hard drive. From there I've loaded all 400 (jpeg), and then just the first 100, into PowerPoint 2007 trying to get the problem described below to go away. No luck. Overall, here's what happens. About half of the pics in the slide window on the left do not appear in the large window on the right. Latest development is the following.

1. I highlight a pic in the slide window on the left hoping it will appear in the window on the right

2. the right, large window remains white (empty)

3.I left click on right window and a large "text" box appears covering almost all of the right window

4. go to the top button on that "text" box and pull it down

5. half way down the window the pic appears in the "text" box (right window) grayed out so it is not clear (like it's hidden behind a layer)

6. at the same time that same pic in the left slide window is half size just like the one on the right

7. release the left click on the right window and the pic in the right window disappears (window returns to white) but the pic in the left window remains half size