Microsoft Messaging Service Still Out

Microsoft Corp. struggled to fix a three-day outage of its instant messaging service that has affected as many as 10 million users of the product, a key component of the software giant’s strategy to offer new Web-based services.

In what MSN Vice President Richard Bray described as an “extremely rare set of circumstances,” the outage was caused by the failure of a disk controller in one of the database computers on which the service is based. A glitch also struck a backup for the controller, he said.

Microsoft hoped to restore service later Friday.

The company’s shares fell $2.45 to close at $66.06 on Nasdaq amid a broad sell-off in technology stocks.