For the operating system to run smoothly, certain files are required. These are called system files and they come with .ini, .bat and so on. All the applications require dll files that contain important information for the application to run. If any of these files are damaged or corrupted, then you have to find a solution for repairing them if you want to use the application further.
If the application dll files are corrupted, then you can try reinstalling the program. Certain applications may be corrupted because of any virus or Trojan accessing the dll files. But if the problem is with the operating system, then more care has to be taken for repairing because without these files, the windows will not run. This does not require reloading the entire operating system, but you have to use the repair process for repairing the files.
Emergency repair process is available with windows that will use the important information with the emergency disk. This option can be used when you have specified this provision while installing the operating system. Otherwise, you can use the windows bootable cd for repairing the operating system. You have to reboot the system using the cd and select repair windows option to start repairing the system files. Once new clean files are installed, windows should start working correctly.