Thanks. My system is running Windows 8.1 Pro, 12 GB RAM, 2TB HDD, Intel i7 processor, NVIDIA GeForce GTX 650 Ti graphics card.
After updating Windows and rebooting, I was able to create a new catalog, then open other catalogs, however, after opening the catalog that became "stuck", the problem returned. Now, when I try to open any other catalog, I am returned to the offending one, since it obviously didn't close properly. I will reboot, and create a different catalog. Since the problem one is small (4500 photos, as opposed to my research catalogs with over 20,00 each) I will recreate it and discard the offending one. I hope this works.
If you have further insights please let me know. I've been using Lightroom since version 1 and didn't have a problem like this until version 4, which forced me to recreate all my catalogs. Let's hope I don't have to.
****!! I just rebooted and clicked Lightroom - I should have been brought to my lisst of catalogs and been asked which one to open, but instead, as I feared, I was brought back to the non-working catalog. What can I do?