I am on a Mac running 10.8.4. I was using C1 7.1.2 with a Catalog. I was having trouble with the software loading so I decided to uninstall 7.1.2 and install 7.1.3, folllowing the instructions on Capture Integration's web page. Now, 7.1.3 opens but it will not load my old catalog. If I click on File/Import Catalog/Another Catalog, the old catalog shows up but it is grayed out. I tried going to Verify Catalog, clicked on Verify, and when it was finished clicked on Open, then it always crashes.
I really don't want to be using a Catalog as I already have a complete Catalog in LR5 that I use as a DAM, but C1 7 leaves me no choice if I want to use C1 to process my files from my IQ180. (No, Sessions are NOT an alternative.)
The import catalog function is to import a catalog from Lightroom.
Use File>Open to open your own catalog.
If you are having issues then the fastest way to solve it is to open a support ticket.
Its hard to diagnose from here!