Gal Civ 2: Twilight Problem

Hello everyone! This is my first time using these boards, so please excuse my newbness.

I'm having an issue updating Gal Civ 2: Twilight of the Arnor, where impulse is asking me to uninstall the version that I have first in order to update, but then tells me that there's a file unavailable and promptly stops. I cannot seem to be able to solve this problems, so I was wondering if any of you have any insight on what I could and should do.

Thanks.