When your Microsoft Office installation is corrupted then you have problems when you are working with some Office applications.

One common problem due to a damaged installation, is that you cannot open (on Double-click) any MS Office documents (Word, Excel or PowerPoint) straight from Windows Explorer and instead of that.

In such cases, the only way to open your documents is by using the File > Open menu or by dragging and dropping your document (Word, Excel or PowerPoint) inside your corresponding Office Application.