Although it does cost money, another tool you could look at to repair the hard drive enough to be able to quickly back up your files before replacement is GRC's SpinRite.http://www.grc.com/sr/spinrite.htm
I've got a site liscense, and, whenever a bad hard drive is suspected, this is one of the first tools I run, because it gives a much more thorough inspection of the hard drive than you could ever do with a file in WINDOWS.
Just run it on Level 2, and it should take care of any of the failing sectors that it sounds as though you have.
Honestly, I've kind of suspected a bad hard drive from the beginning.
Now, I have to say that using this tool should only be used if you're going to back up your files and migrate to a different hard drive. It sounds as though yours is having trouble keeping up as it is, and you might be on the brink of complete and total hard drive failure.
Run SpinRite, if you buy it, of course, and once it's finished, run SFC /SCANNOW
~~If you're so good with computers, how come you're paying me 300 dollars to fix it?~~