Creating boot disk for Windows 7 on MacBook Pro EDIT: I gave in and burned the DVD from a windows PC and I was able to install Windows on my MacBook Pro with Bootcamp. Sorry, that I don't have a satisfying solution.

My goal is to install Windows 7 (32-bit) on my MacBook Pro (late 2007) with Boot Camp. (I'm trying to do all this on Mountain Lion.) I am running into multiple problems creating the disk image for Windows 7. I have an ISO file of the Windows 7 DVD. I am fairly certain, that the ISO image is not corrupted. I downloaded it twice, with the DreamSpark download manager, with the same results.

Initially I tried to create a bootable USB key. The USB key is formatted as Mac OS Extended (HFS+). I opened Disk Utility, went to the restore tab, chose the ISO as source and the USB key as destination. The following errors occurred:


When the ISO-image is unmounted: "RESTORE FAILURE Could not validate source - Invalid argument"
When the ISO-image is mounted: "RESTORE FAILURE Could not validate source - error 254"


After repeating this a dozen times, I tried solve the problem from the Terminal as suggested in many forums:

$ sudo asr restore -noverify -source /path/to/windows/windows_7.iso -target /Volumes/Untitled/ -erase
    Validating target...done
    Validating source...
Could not validate source - Invalid argument


Since this also didn't work, I then tried to burn the image on a DVD. So I went into disk utility, chose the Windows 7 ISO, and chose burn. 

I get prompted


  Waiting for a disc to be inserted…


I insert a brand new DVD-R.The drive starts to do something and notifies me


  Waiting for the drive.


And then immediately ejects the disk again and prompts me for the a disc.
Try using dd instead of asr.


Use mount to determine the device path of your attached USB disk.  Find the disk itself and ignore the individual partition numbers.  EG: if you get /dev/sda1 just use /dev/sda for the next steps.
Unmount the disk in the Finder.  
Construct and run your dd command as such: dd if=/path/to/windows7.iso of=/path/to/usb/device