Error while installing Logic Pro Additional Content HELP!!!!!!!!

Hello, I've recently purchased Logic Pro 9.1.8 from the Appstore on my new MacBook Pro (Mid 2012).

The App installed fine and so did the 2 GB obligatory download on the first launch. But then I downloaded the Logic Pro and Mainstage additional content (4.6

Gb) and then when it started installing, the install window in Logic simply disappeared, I thought it had finished installing, so I checked the Additional content

download menu and it was still unchecked (and without the "Installed" sign on the right). Having copied the package on my external hard drive for backup, I

recopied it on my mac and tried to install, but the installer then displayed the following message: An error occurred while extracting files from the package.

The Log file also included: "The file couldn’t be opened because it isn’t in the correct format."

There isn't an Apple Store in my country.

I'm running on Lion 10.7.5, with 420Gb of free space, please HELP!!!!!!!!