Microsoft's Windows Live Hotmail Webmail service remained inaccessible to a portion of its users for several hours on Friday, but the problem has been resolved.
Windows Live Hotmail, which has about 310 million active users worldwide, became unavailable between approximately 6:30 a.m. U.S. Pacific Time and "late morning," a spokeswoman for Microsoft said via e-mail.
She declined to specify how many users were affected, saying only that the problem affected "a limited set of customers."
The problem, which erupted during maintenance work for Windows Live Hotmail, didn't lead to any loss of data for users, according to the spokeswoman.
Still, the outage led many to report the problem in online forums and blogs. Those affected couldn't log in to their accounts while the problem lasted.
Earlier this month, various Yahoo sites and services, including the main Yahoo.com portal, suffered availability problems that lasted about 90 minutes.