Known error in Office 365 Office Professional plus because of a code defect in the Office Subscription Agent service.
http://support.microsoft.com/kb/2605805
1) With your system locale set to English (United States),
Exit all Office programs
2) run “C:Program FilesCommon FilesMicrosoft SharedOFFICE14OSAUI.exe /f”.
3) Reboot the machine
4) Start the subscription service if not started already (net start osubsvc)
5) you can reset your installation by running the command “osaui.exe /k” from your “C:Program FilesCommon FilesMicrosoft SharedOFFICE14” directory.
6) You’ll be asked to sign in.
7) Be sure to use credentials that match a licensed user account on your Office 365 portal.
