Another program was uninstalled that removed a .dll file that was required by another program or the operating system.
A program was installed that overwrote the .dll file with either an older version or a version that is incompatible with other programs causing .dll errors.
A bad installation of a program corrupted one or more files causing the .dll errors.
Another user or program maliciously or mistakenly deleted the .dll file or an associated file.
A hardware issue exists with the computer, such as a bad hard disk drive, causing the data on the drive to become corrupt, casing the .dll errors.
Try booting in safe mode then do the following steps
Type "sfc /scannow" and press enter.
Once you've done this, Windows will verify that all protected windows files are intact or not.
You may need to copy any missing files from the installation disc