Can you at least start in safe mode?
If you can, you have a copy in
\windows\system32\dllcache
Copy it to \windows\system32
If you can't start is safe mode, get a linux bootable CD and boot from it. It can be downloaded from several places. Some stores also have them, usualy available for free.
It won't change anything on your system, it will run entirely from RAM.
Mount the C:\ drive and navigate to \windows\system32\dllcache and proceed as above.
If that don't work, use the Linux cession to backup as much as possible of your documents and medias to somewhere safe.
As you have access to another computer, there is a possibility of taking your OS drive and connect it into another computer. As in that computer nothing is set to use your drive, it will not change anything and your drive will not interfere with the installed OS.
Do the copy as stated above.
Get the drive back in your computer. Boot.
If that don't work:
Reinstall windows and restore your datas.
Electro
April 2011