Thanks for the log file, Mark.
It's looking like something has gone awry with one of the database files. Make sure Photo Mechanic Plus isn't running and then do the following:
In the Finder choose "Go to Folder..." on the Go menu. Copy and paste the following into the "Go to the folder:" field:
~/Library/Application Support
And click the "Go" button. Then open the "Camera Bits, Inc" folder followed by the "Photo Mechanic" folder. Finally, open the "catalog" folder followed by the "state" folder.
There should be a "cat_state.sq3" file in the "state" folder. Rename it by putting an 'x' at the start of its name.
Launch Photo Mechanic Plus. It should now launch.
You will need to do a "Locate Existing Catalog..." on each of your catalogs, and once they're acquired you'll have to perform a "Reintegrate Forgotten Catalog..." maintenance operation on each of them. You can do both of these tasks in the Catalog Management window. (Catalog->Manage Catalogs...)
The Locate Existing Catalog... button is near the bottom of the "Local Catalogs" area. Maintenance is done per-catalog, and to get to it, you click on the triangle to the left of each catalog name. This will reveal some controls and another expandable area labeled "Maintenance". Click on the triangle to expand Maintenance. Then click on the "Reintegrate Forgotten Catalog" button. Do this for each of your Catalog(s).
HTH,
-Kirk