Tried looking around for an answer, but no luck.
I have dozens of photos with an X in the top left corner of the photo with the file name in various albums. I ran the debug from the photo like the guide suggested but I have not a clue what it means. All of the photos are from the same setting and the same camera. Any help would be much appreciated. Thank you!

Album: [ pathname ], Image: [ DSC00546.JPG ]

Image filesize: 4376520

Debug i.php | Arguments:

size = 595
width =
height =
cw =
ch =
cx =
cy =
quality = 85
thumb =
crop =

Fatal error: Allowed memory size of 100663296 bytes exhausted (tried to allocate 10944 bytes) in /pathname/zp-core/lib-GD.php on line 325

http://www.zenphoto.org/news/why-are-some-of-my-thumbnails-sized-images-not-generated-why-does-zenphoto-make-my-server-crash-while-processing-images-

Ok I read it. I understand it. However, doesn't make a lot of sense. Like I said every photo is the same with the same pixels, etc. It's just a hand full of photos in each album. Over the different versions of ZenPhoto I've had this issue and when a new version comes out, I upgrade, and then everything works fine. For whatever reason it's not working so great this time around.

Ok I figured out the problem. When the photo is displayed as sideways for example a picture of a face the head is going from left to right instead of up and down it won't display. When I change the picture to clockwise until the head is up and down and reupload the image it works. Does that make sense? Is that a bug? Anyone else experience that?

Here's another update:
When the auto roate image is unchecked everything works fine. When checked and the image is sideways is when the error comes back.
Is that normal?

It would appear that you do not have sufficient memory to perform the rotation of those images. That is indeed an extra step in the processing.

Ehhh...that sucks. What is the min. memory requirements to make this feature work? When I log into admin it displays this:
PHP memory limit: 96M (Note: Your server might allocate less!)
Is this the memory you’re talking about or actual physical server memory?

I do not really know what memory would be needed. But the GD library is notoriously wasteful of memory. If you have IMagick available on your site you should try it as it is reported to be much better at memory usage.

It does appear (from your error message) that the 96M memory is indeed what you have available. You can try upping that limit in your PHP.ini file. However, note that as the message does say, that setting is a "suggestion" and the server can ignore it.

How do you change to IMagick? I saw something to go to options/Image but I didn't see any option to switch. Thanks.

Unfortunately, if there is no option that is an indication that IMagick is not installed on your site.