Microsoft Warns of Windows Security Flaws

Microsoft Corp. warned consumers about four critical new flaws in its popular Windows software as the company shifted to monthly alerts for serious problems that could let hackers break into computers.

In particularly embarrassing disclosures, Microsoft acknowledged problems in its technology to authenticate software publishers over the Web and in its Windows help and support system. Microsoft also announced a fifth, less serious Windows vulnerability. The company said it did not believe hackers were yet exploiting the vulnerabilities.

Separately, Microsoft said it began allowing its employees to decide to sell stock options to J.P. Morgan Chase & Co. Employees have until Nov. 12 to decide on options that have an exercise price of $33 or higher.

Microsoft shares rose 39 cents to $29.07 on the NYSE.