Try uninstalling Microsoft Office and deleting all registry entries, then reinstalling and see if you get the same problem. To find the entries, after deleting Microsoft office open your start menu>run.
Then when the window pops open type in 'regedit' and hit run.
Within regedit hit ctrl + f and type in office, delete all registry entries that pop up.
Repeat the last step but instead of office search for word, excel, powerpoint, etc until it cannot find anymore entries that coincide with your choices.

After all of this is done reinstall Microsoft Office.