When I try to do so I get the following error message : The Lightroom catalog named “Lightroom 4 Catalog” cannot be opened because another application already has it opened. (Quit the other copy of Lightroom before trying to launch) Choose a Different Catalog Continue Exit
This error occurred when I needed to do a forced shut down of the system as it locked up. I had Lightroom open at the time. I'm assuming that the program thinks I still have it open for some reason...
I've tried the Adobe troubleshooting tips, none help...
Please help me!
Please close Lightroom and Go to the folder Pictures/Lightroom ,In there you should find a file Lightroom 4 Catalog.lract.lock. This is the temporary lock file which is created when a catalog is opened
Delete this file and restart Lightroom
Let us know if that helps