Dear Aunt TUAW,
Help! I can't install anything after my Xcode install failed. Every time I try, Installer tells me that it's waiting for other installations to complete and then it just sits there forever.
What can I do? I've tried rebooting, I've tried killing the installer daemon. I'm at my wits end.
Please save me, Auntie!
It's okay. Deep breaths. Nothing to panic about. Fixing a failed install is actually pretty easy, so long as you don't mind waiting for a full system reboot. Here's what you do.
First, hop into Terminal and change directories over to /private/var/db/mds/system. Then remove the mds.install.lock file (you'll need to sudo rm, so be prepared to authenticate as root). Finally, reboot your system (sudo reboot).
You should be good to go.