"Microsoft is investigating reports of a limited number of instances in which Windows Live customers may have access to other customers' accounts when accessing their account through mobile Web browser," the company said in a statement Tuesday. "Microsoft takes customers' privacy seriously, and immediately upon learning of these reports, we started an investigation."
The Microsoft Live sign-in was unavailable for about an hour Tuesday. No word if the two incidences are related.
The company added that it "will take appropriate action once we have completed the investigation."