Details of the gWindows Live glitch are sketchy, but some reports suggest that a partial server shutdown on the service early yesterday evening (UK time) ramped up the load on the remaining servers, causing an information overload, triggering user sessions to be randomly accessed.
This type of server overload situation was quite common in the early days of the internet, especially in the mid-to-late 1990s, when web access really started to take off, Infosecurity notes.
Microsoft appears to have responded to users' reports of the server overload on Twitter and other social networking sites by taking some of the affected servers offline.
In a message posted overnight on the Windows Live service, the software giant said: "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."
"Microsoft takes customers' privacy seriously, and immediately upon learning of these reports, we started an investigation", the posting added.
Microsoft's Windows Live feature supports more than 450 million users worldwide.