When I click on some of my photos in Iphoto they "black out". why is this?

Possible the wrong colour profile. But that amount of information leaves nothing to work with so:

There are 9 different versions of iPhoto and they run on 10 different versions of the Operating System. The tricks and tips for dealing with issues vary depending on the version of iPhoto and the version of the OS. So to get help you need to give as much information as you can. Include things like:

- What version of iPhoto.

- What version of the Operating System.

- Details. As full a description of the problem as you can. For example, if you have a problem with exporting, then explain by describing how you are trying to export, and so on.

- History: Is this going on long? Has anything been installed or deleted? - Are there error messages?

- What steps have you tried already to solve the issue.

- Anything unusual about your set up? Or how you use iPhoto?

Anything else you can think of that might help someone understand the problem you have.

If these photos were in a folder on your system and you then imported them - in advanced settings on IMPORTING are you Copying the items into the IPHOTO library? If unchecked - IPHOTO only takes in the location of the picture.