As long as the computer shipped with a valid copy of Windows 7 you may be able to fix it.
You will have to use a separate computer and go to Digital River, found HERE
, and download the corresponding ISO file that is appropriate to your computer.
You should still be able to perform the reformat but you may have to download the drivers, etc. from Acer's support site.IMPORTANT NOTE:
If the product key attached to the computer is invalid or black-listed, the ISO will not install correctly.
I would recommend creating a Hirens Boot CD
and utilize some of the options available to run a HDD diagnostic on the hard drive of your computer because with it hanging at that percentage usually indicates potential damage to the internal components of some sort since it was booting from the hidden partition which is normally at the beginning of the drive itself.