The issues began around 5pm UK time, with almost 2,500 reported incidents occurring in a short space of time according to website downdetector.com.
These latest issues follow on closely from authentication problems earlier this month with both Outlook and Skype. Microsoft told V3 at the time: "We are aware of reports that some users are having difficulty signing into some services. We are investigating this issue."
Some users are reporting problems with other Microsoft services including its XBox gaming platform.
This latest issue coming so soon after previous problems has left some Microsoft customers frustrated, and they have been quick to share their thoughts over social media.
Others posted evidence of their troubles.
"We are aware that some users are experiencing difficulties signing in to some services. Engineers are working to fully resolve this as soon as possible," a Microsoft spokesperson added.
'We are making good progress on 10nm,' claims Intel
Engineer calculates that Chengdu's plan to replace streetlights with artificial moonlight would cost $100bn
Research could also apply to other 'space weather' events involving hot, fast-moving plasma
Dark matter holds the Universe together - and gravitational waves could help identify it