A Microsoft file hosting and synchronization service.
Hello,
When exactly do you receive the error message? Also mention the exact and complete error message you receive?
You may also provide a screen shot of the issue to assist you better.
Meanwhile, you may repair the Office 2013 installation and check if it helps resolve the issue:
http://office.microsoft.com/en-in/project-help/repair-or-remove-office-HA010357402.aspx
Do get back to us with the results, so that we may assist you further.
Thank you