Is there anything more annoying than not being able to open your email? Overnight, Microsoft's Outlook and Hotmail users found themselves locked out of their inboxes for a long stretch, before the problem was finally resolved on Wednesday. Microsoft hasn't explained what caused the outages, which began at about 2:30 p.m. Tuesday PT. 

As usual, users vented on Twitter en masse. At around 7:30 a.m. PT Wednesday, Microsoft fixed the problem and notified users via its status page. The outage lasted more than 17 hours and affected SkyDrive as well. 

In a statement sent to CNET, Microsoft only acknowledged an outage but stopped short of saying what was done to prevent it from happening again.

"Hotmail and Outlook.com experienced an outage that affected customers' access to their email," the statement read. "Fortunately the issue has been resolved and service is now restored to normal. We sincerely apologize for any inconvenience this caused our customers."

This is not the first time that Outlook and Hotmail have been down. It happened in January and lasted several days. It may have something to do with Microsoft replacing Hotmail with Outlook.com, which was inaccessible to some users. Still, more than 60 million are using Outlook.com as of February, The Register reports. 

Contrary to Microsoft's struggles, Google's Gmail and Google Drive are consistently reliable, which probably doesn't bode well if Outlook.com is to retain users.