If the version of the concert you´re try to load is different than yours than probably that´s the problem.
Some missing plug-in may lead to it. Can you tell what´s the content of the concert? guitar setup, how many patchs, etc.
You could try this:
Export (Command + E) each patch or export the set by click on it
Then Import (Comand + I) it to a new concert in your Mac
Post your results
Hope i´ve helped you