Alright, here's the thing, I downloaded an ISO file, and, upon opening it, found out that it was not what I wanted. No big deal, I deleted the second CD and tried deleting the second, however, every time I try to, it says that the file is in use by another program. I have tried everything, including booting into safe mode, restarting the computer, etc, to try and delete this file, and it always says that another program is using it. I have scanned it and my windows folder for viruses, and found nothing.
It's taking up a good 700 megs of space on my drive, and it'd be great if someone could help me with removing it

EDIT: Upon running a system restore, the file has dissappeared, however, I am now missing three gigs worth of space!