Crashing after Snow Leopard Downgrade

I recently downgraded from Lion to Snow Leopard because of a hardware issue and ever since, Logic Express has not been able to open. It is version 9.1.5. My OS is 10.6.8. When I try to open Logic, I get the message "Logic Express cannot be opened because of a problem. Check with the developer to make sure Logic Express 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." I have reinstalled Logic several times, but it hasn't helped. Also, I've noticed iPhoto gets the same message when I try to open it. Could there be a link? Anyone know what I can do?

Thanks