Non-descript error when installing ML

Hi all,

I've been struggling with getting my 2012 21.5" iMac going. It was passed along to me, and so I wanted to do a clean reboot of the OS. I was able to successfully erase and partition the HDD, but when it came time to reinstall ML, I get the following error:

"An error occurred while preparing the installation. Try running this application again."

This error pops up after I have selected the target disk.

As a curious note, the first time I tried, it got about 30% of the way before saying "Unable to download additional components needed...". Every attempt after that has led to the above error.

Any ideas would be much appreciated!