Iphoto

We are using IPhoto (version 8.1.2). Since recently we cannot open our iPhoto library anymore. When we open iPhoto it says:
The photo library needs to be upgraded to work with this version of iPhoto.
Your photo library will not be readable by previous versions of iPhoto after the upgrade. The upgrade process may take several minutes depending on the number of photos in the library.
after choosing <upgrade> (the other option <quit> does not help us) the following text appears:
You can’t open your current photo library using this version of iPhoto. You have made changes to your photo library using a newer version of iPhoto. Please quit and use the latest version of iPhoto.

I am lost and I do not know how to approach my photo's anymore. Anyone who can help me out?
Tnx

The latest version of iPhoto is 9.4.2. Have you tried to run software update in order to update your copy of iPhoto? Also, which version of OS X are you running?

Thanks!
I am using version OSX 10.6.8. I have not yet changed to Life11, iPhoto 9.4.2. I do not want to change yet because we have to change hard disk in the very near future. I am afraid we do not have a choice though...