iWork Pages problem

I purchased and installed the iWork disk to my iMac a few months ago. Was working fine. Somehow my 12yo son was working with pages and it is now gone...could not find it anywhere. I reinstalled iWork and now when I try to open pages is give me the following message "Pages cannot be opened because of a problem.Check with the developer to make sure Pages works with this version of Mac OS X. You may need to reinstall the application. Be sure to install any available updates for the application and Mac OS X."

It will not open at all....I have even tried to install it a 3rd time and got the same results

What do I need to do?

Try to completely uninstall the iWork suite first and then reinstall. It's possible that there are corrupted files left over. Reinstalling will not remove any files that are corrupt. Use "Spotlight" (the small magnifying glass from the top menu) to find all the iWork files. You're probably going to have to remove Keynote and Numbers also along with Pages. In other words, the entire suite.

Thanks chscag.....that eventually worked. I had to install a few software updates after the re-install, but everything seems to be working fine.....much appreciated!!