Sign in with the account you use for SkyDrive, Xbox LIVE, Outlook.com, or other Microsoft services.
Sign in with the account provided by your work or school to use with Office 365 or other Microsoft services.
You try to use a command on the ribbon, but the command is disabled or unavailable.
It’s possible that your administrator has disabled this command through group policy.
Other possible causes are:
You don't have permission to the file
The file is in Reduced Functionality Mode
The file opened in Protected View
Contact your administrator. If you are the administrator, see the Office 2010 Resource Kit.