Issues with copying files from install

[athenahollow]

I bought Penumbra: Overture in the Humble Indie Bundle today and every time I go to install I get this error:

An error occurred while trying to copy a file:
The source file is corrupted.

on these files:

character_dog_walk.collcach
character_rockworm_base.collcach
character_rockworm_idle.collcach
character_spider_attack.collcach
character_spider_base.collcach
character_spider_death.collcach
character_spider_idle.collcach
character_spider_walk.collcach


I don't know if they are important or not, so I just cancel the install after I click ignore enough to get through those files.
I tried re-downloading the file to no avail. Same issue.

Any advice?

Thanks for your time

-Athena Hollow