How to fix a Microsoft Word MSO.DLL Error
Mso.dll is a dynamic link library created by Microsoft and used by the Microsoft Office programs. Mso.dll errors appear as pop-up windows that generally state something along the lines of "Mso.dll was not found" or "Mso.dll is missing." Generally, these errors are caused by a missing or corrupt mso.dll file and can be fixed by re-installing the Mso.dll file. To complete this task, you may need an administrator name and password.
Download Mso.dll onto your desktop from one of the many online dynamic link libraries at ll-download.net and afreedll.com.
Click "Start" and "Computer."
Double-click "C: Drive," "Windows" and "System32." The System32 folder opens.
Drag the Mso.dll file on your desktop into the System32 folder.
Click "Start," type "cmd" into the search field and press "Enter" to open the Command Prompt.
Type "regsvr32 mso.dll" (without the quotation marks) into the Command Prompt and press "Enter."
Close the Command Prompt and restart your computer.