Isso é estranho, com certeza. :)
Talvez tente o reparo do Office recursos:
Repair your Office programs by doing the following:
- Click Start, then click Control Panel.
- Click Programs and Features.
- Click the Office program that you want to repair, then click Change.
- Click Repair, then click Continue.
You might need to restart your computer after the repair is complete.
Você também pode executar o Diagnóstico do Office indo para Start-->Programs-->Microsoft Office-->Microsoft Office Tools-->Microsoft Office Diagnostics
.