I keep getting this message: "The Lightroom catalog named "Lightroom 3 Catalog" cannot be opened because another application already has it opened. Quit the copy of Lightroom before trying to launch." If only it were true! Another app does NOT have it opened. It does not appear in "Task Manager," and I have started and restarted my computer several times--including just forcing it off using the power button, and every time I try to access lightroom, I get this message. Any ideas?
You need to go at the location where you Lightroom Catalog is stored and delete the .lock file (remember not to delete .lrcat file)
then, try to launch Lightroom.
By default, catalog is stored under Pictures\Lightroom.