SAN FRANCISCO -- Microsoft is trying to fix a technological breakdown that has cut off some people from their email accounts on Outlook.com and files stored on the company's SkyDrive service.

The Redmond, Wash., software maker says only a small number of people have been affected by an outage that began Wednesday morning. Microsoft's statement about the problem didn't provide any further specifics.

Even if only a small percentage of Outlook.com users are cut off, the trouble could be frustrating millions of people. Microsoft boasts it has more than 400 million accounts on Outlook.com.

Microsoft Corp. transferred all the users of its other Web email, including those with the hotmail.com and msn.com domains, to Outlook earlier this year as part of its attempt to outshine Google Inc.'s Gmail and Yahoo Inc.'s email.