Some of the selection criteria on the IC Slow Moving Items report seem to depend on the Period-to-Date and Year-to-Date statistics, however, the Period End and Year End have not been run in some time.

I need to know if it is possible to go back and run the old Period and Year Ends so that the Slow Moving Items report will produce meaningful results?

Dakota Software has an Adagio Toolkit module to recalculate Item sales history. Double check with Bob Wisener, but I think it'll do what you're after.