If you are getting error messages when you launch a particular app, the chances are high that the file may be corrupt or missing. The solution is simply uninstalling the app and then reinstalling it from the installation disk. The other option
This confusion could have occurred because of a lack of knowledge about file indexes in general, or confusion regarding 32-bit and 64-bit versions of Windows. 32 bit and 64-bit versions are completely different architectures of Windows that are developed in every iteration.