Microsoft's Hotmail service has been down for some users for almost an hour, without much explanation for the outage.
At the time of writing on Friday morning, the webmail tool had been out of service for 55 minutes, according to the crowd-sourced downrightnow service. Some users on Twitter are reporting that Hotmail is working for them, though.
Many people trying to log into Hotmail are seeing a message reading: "It looks like there's a problem with Windows Live Hotmail right now. We're working hard to fix it, but it may take a little while longer."
The note includes a link to a 'support' article that informs the user that there is a temporary problem with Hotmail, with not much more in the way of useful information.
Other Windows Live services, such as SkyDrive and Messenger, appear to be operational at the time of writing, even for those not able to access Hotmail..
A three-hour Hotmail outage occurred earlier this month, although SkyDrive and Office 365 were also down on that occasion.
UPDATE: As at 10:27am, Hotmail appears to be up and running again.