Bad "image" file

I installed software from online and when I rebooted my
system asked for the dynamic link library mfc42.dll in
several of the directories. I transfered the file from the
Windows 2000 Pro cd onto a floppy and then into those
directories. All the directories but one was ok, the
C:\windows\system32 brought up an error message
stating "bad image" and refering to the mfc42.dll file. It
needed the installation disk. How can I fix this problem
and still maintian the information on my hard disk? Do I
need to reinstall windows?
.

 

Description of the Windows 2000 Windows File Protection Feature