Currently Being ModeratedFeb 3, 2013 7:04 AM (in response to asincero)
If you attempted a clean install, you erased the disk. If the Mac shipped with Lion, which it probably did, you'll need to re-install Lion before installing ML.
EDIT: Wait...where did "the copy of ML that's already on the machine" come from?
Currently Being ModeratedFeb 3, 2013 8:09 AM (in response to asincero)
Machines which originally ship with Mac OS X 10.8.2 use a machine-specific build; until Mac OS X 10.8.3 is released, the generic version in the Mac App Store won't work on them. The Internet Recovery method is the only way to do a clean install at this time.
Currently Being ModeratedFeb 3, 2013 8:46 AM (in response to macjack)
This is a late-2012 iMac, so it has Mountain Lion (10.8.2 to be exact) already on it.