I ran into this problem I personally haven’t seen before.
I downloaded an installation file from LogMeIn. The file downloaded as a .ZIP which I was able to open and out came a .pkg file. When I clicked on the .pkg file, my Terminal window would open. I had no idea what to do. Perhaps a file association was broken? I’ve seen this in Windows plenty of times and familiar with repairing the association. So how to you do this in Mac OS X?
So to fix this problem, you need to assicate the .pkg with the Installer application. Where did you look for it? It’s located in /System/Library/CoreServices/. Select a .pkg file. Press COMMAND-I to open the Get Info window. In the Open With panel select the Installer if it’s listed or find it in the /System/Library/CoreServices/ folder. Select it then click on the Change All button.
This fixed my issue, hopefully it get you out of this bind!