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REDMOND, WASHINGTON (BNO NEWS) — Windows Live Messenger Services and its websites, including Hotmail, are back online after suffering from an hour-long outage on Tuesday afternoon.

Many users, most of them in Europe and Asia, reported receiving a “service unavailable” error when attempting to sign in to Windows Live Messenger, an instant messaging system developed by Microsoft in 1999. The service is best known as MSN, its former official name.

Users were also unable to access the Messenger-related websites, including sites such as Hotmail.com. It was not immediately clear how many users were affected during the outage, which was resolved just after 1 p.m. EST.

“We are aware that some Windows Live customers may be experiencing difficulty accessing their accounts, and are working aggressively to address the situation as rapidly as possible,” a spokesperson for Microsoft said. “We sincerely apologize for any inconvenience this may be causing our customers.”