Microsoft’S Hotmail Bogs Down

Microsoft Corp. said its free e-mail service, Hotmail, has been having problems because of system upgrades.

Microsoft said a limited number of customers may have had problems in the past week logging on or being logged out of Hotmail. The company didn’t release specific numbers.

Microsoft said the upgrades are part an effort to improve Hotmail service, which has 84 million users and was bought by the software company in 1997.